This document provides a summary of various methods for synthesizing pyridine rings, focusing on ring-construction reactions. It describes several approaches including the condensation of 1,5-dicarbonyls, the Hantzsch synthesis, reactions of 1,3-dicarbonyls with 3-aminoenones, the Kröhnke annulation, Diels-Alder reactions with 1-azadienes, inverse electron demand Diels-Alder approaches using isoxazoles, pyrimidines, and 1,2,4-triazines, and cobalt-catalyzed [2+2+2] cycloadditions. Examples of applications in natural product syntheses are provided
The document discusses two approaches towards synthesizing graphene nanoribbons (GNRs): the ceramidonine approach and the Perkin approach using cyclodehydrogenation. The ceramidonine approach allowed synthesis of some electron acceptor-type, soluble tetraazaarene ribbons but had difficulties with cyclization reactions and incorporation of solubilizing chains. The document then discusses using the Perkin reaction to synthesize diacrylate monomers, followed by cyclodehydrogenation with DDQ/MeSO3H to form polycyclic aromatic ribbons. Sixteen different diacrylate monomers were synthesized and subjected to cyclodehydrogenation conditions, yielding several cyclized ribbon products.
Synthesis of 3-Substituted Coumarins by the Knoevenagel Condensation Reactionmariam1020
The document summarizes a study on the synthesis of 3-substituted coumarins via the Knoevenagel condensation reaction of various 2-hydroxyaldehydes and malonate esters under solvent-free conditions using silica gel or basic alumina as catalyst. The reaction was carried out using microwave irradiation. Various coumarin products were obtained in moderate to good yields and characterized using techniques such as IR, NMR, and GC-MS. The method provides an improvement over traditional Knoevenagel condensation reactions through the use of solvent-free conditions and microwave activation.
This document describes the catalysis of substitution reactions on heterocycles bound to a solid phase. It discusses immobilizing 2,6-dichloropurine on a Rink resin, performing C6-substitution with various amines in high yields, and C2-substitution via palladium-mediated coupling reactions such as Suzuki and amination reactions. It also investigates modifying the polymeric support by treating it with a brominating agent to install bromine complexes on the resin for further substitution chemistries. The reactivity of the bromine complex is explored, finding it performs selective side reactions in dry benzene that are not possible in NMP solvent.
The document describes a PhD thesis focused on developing the Nazarov reaction for organic synthesis. The thesis includes efforts to synthesize the natural product roseophilin using Nazarov chemistry, studies on making the reaction asymmetric, and other applications of the reaction.
This document provides an overview of homogeneous catalysis and biocatalysis. It discusses various homogeneous catalysts including Wilkinson's catalyst, Ziegler-Natta catalysts, and catalysts used in hydrogenation and hydroformylation reactions. It also discusses the use of enzymes in organic synthesis, including hydrolysis reactions and the synthesis of tartaric acids. Finally, it covers immobilized enzymes and various methods for enzyme immobilization.
Novel approach to synthesis of pentofurano nucleoside assisted natural phosph...Alexander Decker
This document describes a novel method for synthesizing various ribonucleosides using natural phosphate doped with CF3SO3H (NP/CF3SO3H) as a catalyst. Several ribonucleosides were prepared from 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranoside and silylated nucleobases under mild conditions using NP/CF3SO3H. The reaction proceeded through an oxonium intermediate to provide the desired nucleosides in good yields ranging from 20-35%. The method was found to be regioselective, stereoselective, simple, efficient and environmentally friendly for synthesizing various D
The document provides solutions to sample problems from Chapter 10 on nucleophilic substitution at the carbonyl group. The first problem suggests reagents to synthesize the drug phenaglycodol in three steps: addition of cyanide to a ketone, addition of an alcohol to the nitrile, and double addition of an organometallic reagent to an ester. The second problem explains why direct ester formation from carboxylic acids and alcohols works in acid but not base, while other methods use base. The third problem predicts the success of potential carbonyl substitutions based on leaving group pKa values. The last problem provides mechanisms for reactions involving an amine, alcohol, and acid chloride.
The document discusses two approaches towards synthesizing graphene nanoribbons (GNRs): the ceramidonine approach and the Perkin approach using cyclodehydrogenation. The ceramidonine approach allowed synthesis of some electron acceptor-type, soluble tetraazaarene ribbons but had difficulties with cyclization reactions and incorporation of solubilizing chains. The document then discusses using the Perkin reaction to synthesize diacrylate monomers, followed by cyclodehydrogenation with DDQ/MeSO3H to form polycyclic aromatic ribbons. Sixteen different diacrylate monomers were synthesized and subjected to cyclodehydrogenation conditions, yielding several cyclized ribbon products.
Synthesis of 3-Substituted Coumarins by the Knoevenagel Condensation Reactionmariam1020
The document summarizes a study on the synthesis of 3-substituted coumarins via the Knoevenagel condensation reaction of various 2-hydroxyaldehydes and malonate esters under solvent-free conditions using silica gel or basic alumina as catalyst. The reaction was carried out using microwave irradiation. Various coumarin products were obtained in moderate to good yields and characterized using techniques such as IR, NMR, and GC-MS. The method provides an improvement over traditional Knoevenagel condensation reactions through the use of solvent-free conditions and microwave activation.
This document describes the catalysis of substitution reactions on heterocycles bound to a solid phase. It discusses immobilizing 2,6-dichloropurine on a Rink resin, performing C6-substitution with various amines in high yields, and C2-substitution via palladium-mediated coupling reactions such as Suzuki and amination reactions. It also investigates modifying the polymeric support by treating it with a brominating agent to install bromine complexes on the resin for further substitution chemistries. The reactivity of the bromine complex is explored, finding it performs selective side reactions in dry benzene that are not possible in NMP solvent.
The document describes a PhD thesis focused on developing the Nazarov reaction for organic synthesis. The thesis includes efforts to synthesize the natural product roseophilin using Nazarov chemistry, studies on making the reaction asymmetric, and other applications of the reaction.
This document provides an overview of homogeneous catalysis and biocatalysis. It discusses various homogeneous catalysts including Wilkinson's catalyst, Ziegler-Natta catalysts, and catalysts used in hydrogenation and hydroformylation reactions. It also discusses the use of enzymes in organic synthesis, including hydrolysis reactions and the synthesis of tartaric acids. Finally, it covers immobilized enzymes and various methods for enzyme immobilization.
Novel approach to synthesis of pentofurano nucleoside assisted natural phosph...Alexander Decker
This document describes a novel method for synthesizing various ribonucleosides using natural phosphate doped with CF3SO3H (NP/CF3SO3H) as a catalyst. Several ribonucleosides were prepared from 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranoside and silylated nucleobases under mild conditions using NP/CF3SO3H. The reaction proceeded through an oxonium intermediate to provide the desired nucleosides in good yields ranging from 20-35%. The method was found to be regioselective, stereoselective, simple, efficient and environmentally friendly for synthesizing various D
The document provides solutions to sample problems from Chapter 10 on nucleophilic substitution at the carbonyl group. The first problem suggests reagents to synthesize the drug phenaglycodol in three steps: addition of cyanide to a ketone, addition of an alcohol to the nitrile, and double addition of an organometallic reagent to an ester. The second problem explains why direct ester formation from carboxylic acids and alcohols works in acid but not base, while other methods use base. The third problem predicts the success of potential carbonyl substitutions based on leaving group pKa values. The last problem provides mechanisms for reactions involving an amine, alcohol, and acid chloride.
1,4- Addition of copper acetylides to unsaturated ketonesSaibalendu Sarkar
TMSI promoted 1,4-addition of Copper acetylides to unsaturated aldehydes and ketones.This ppt is totally based on a paper published in Journal of American Chemical Society. The ppt is more about the analysis of the paper
This document provides an overview of 9 organic reactions: 1) Metal hydride reduction using NaBH4 and LiAlH4, 2) Clemmensen reduction, 3) Birch reduction, 4) Wolff-Kishner reaction, 5) Oppenauer oxidation, 6) Dakin reaction, 7) Beckmann rearrangement, 8) Schmidt rearrangement, and 9) Claisen-Schmidt condensation. For each reaction, it discusses the reaction mechanism, modifications, and applications in organic synthesis and drug development. The document serves as a reference for graduate students and researchers on important carbonyl reactions and their uses in pharmaceutical chemistry.
The document discusses various methods for forming C=C double bonds, including aldol condensation, Wittig reaction, Peterson olefination, and Julia-Lythgoe olefination. It also covers carbonyl coupling reactions, Tebbe reagent, Shapiro and related reactions, eliminations, conversions of diols and epoxides to olefins, and transformations of acetylenes and existing olefins. Specific examples and reaction conditions are provided for many of these C=C bond forming methods.
Photochemistry of carbony compounds.pptxssuserb017d1
- Carbonyl compounds absorb UV light at wavelengths of 280, 195, 170, and 155 nm, with the 280 nm band being important for photochemistry. This absorption corresponds to an n-π* transition.
- Upon absorption of UV light, carbonyl compounds can undergo four types of reactions: α cleavage, β cleavage, hydrogen abstraction, and addition to carbon-carbon multiple bonds. α cleavage (Norrish type I reaction) is the most common.
- In the Norrish type I reaction, absorption of UV light leads to cleavage of the carbonyl carbon-α carbon bond, forming an acyl radical and an alkyl radical. These radicals can then undergo secondary reactions like decarbonylation or hydrogen abstraction.
This document describes an unprecedented C-methylation reaction at the 2-position of 4-chromanone-2-carboxylates using the Corey–Chaykovsky reagent (dimethylsulfoxonium methylide, DIMSOY). Treatment of various 4-chromanone-2-carboxylates with DIMSOY results in good yields of the corresponding 2-methylated products, rather than the expected epoxide formation. Computational calculations provide evidence that the reaction proceeds through cisoid addition of DIMSOY to the carbonyl, formation of a betaine intermediate, and methyl transfer to C2 via a transition state, enabled by the basic nature of DIMSO
Sulfonium-Ion Glycosidase Inhibitors and Their DerivativesAndeChennaiah
This document summarizes research on naturally occurring sulfonium-ion glycosidase inhibitors and their derivatives. It outlines the synthesis of several inhibitors including salacinol, kotalanol, and ponkoranol. Various analogs of these inhibitors were also synthesized to investigate structure-activity relationships. Enzyme inhibition studies showed that some analogs maintained similar inhibitory activity to the natural products, while others showed reduced or no activity. In conclusion, discoveries in this field of sulfonium-ion glycosidase inhibitors have increased in the last 20 years, with some molecules considered as potential diabetes therapeutics. However, the area remains young with opportunities for chemists to develop novel inhibitors.
This document discusses ozone chemistry and the Wittig reaction. It describes the mechanism of ozone addition to double bonds, forming primary and secondary ozonides. The key intermediate in the mechanism is the zwitterion. It also discusses using nucleophilic reduction of secondary ozonides to form carbonyl compounds such as aldehydes and ketones. The Wittig reaction involves using ylides derived from phosphonium salts to displace oxygen from ozonides. This project investigated the cis/trans isomerism and solvent effects of Wittig reactions using three different ylides and solvents in one-flask syntheses of cinnamonitrile, benzylidene succinic anhydride, and methyl cinnamate
This document discusses metathesis reactions and their applications in organic synthesis. It begins with definitions and examples of different types of metathesis reactions including alkene, alkyne, and enyne metathesis. It then covers the key catalysts used, such as Grubbs and Schrock catalysts, as well as the 2005 Nobel Prize awarded for the development of metathesis reactions. The document concludes by outlining several important applications of metathesis in synthesizing biologically active compounds and natural products.
Crown ethers
NOMENCLATURE
GENERAL SYNTHESIS OF CROWN ETHER
AZA CROWN
CRYPTAND
APPLICATIONS
1. SYNTHETIC APPLICTION
Esterification
Saponification
Anhydride formation
Potassium permanganate oxidation
Aromatic substitution reactions
Elimination reactions
Displacement reaction
Generation of carbenes
Superoxide anion
Alkylations – 1. o-alkylations
2. c-alkylations
3. n-alkylations
2. ANALYTICAL APPLICATION
Determination of gold in geological samples
Super critical fluid extraction of trace metal from solid and liquid materials
Application of ionic liquids in analytical chemistry
Oxidation and determination of aldehydes
Crown ethers are used in the laboratory as phase transfer catalyst
OTHER APPLICATION
It is used in photocynation
Resolution of racemic mixture
Benzoin condensation
Hetrocyclisation
Synthesis of furanones
Acetylation of secondary amines in presence of primary amine
The document discusses the synthesis of heterobimetallic NHC ligand based complexes and their catalytic applications. It describes various methods for synthesizing these complexes using triazolylidene and imidazolylidene ligands to link two metal centers. Testing of the complexes showed that combining two metals into a single ligand framework often provides better catalytic performance than using a mixture of homometallic complexes. The binding site of the metals, whether as N^N chelate or NHC, was also found to influence catalytic activity.
This document summarizes a seminar on photochemistry presented to the Department of Chemistry Post Graduation Center. The seminar covered various types of photochemical reactions including photoreduction, photoisomerization, photochemical substitution, photodimerization, and photolysis of carbonyl compounds. Photochemistry involves chemical reactions that are initiated by the absorption of light, most commonly in the visible or ultraviolet regions. A variety of reaction types such as reduction, synthesis, and isomerization can be induced photochemically. Examples of specific photochemical reactions discussed include the reduction of benzophenone to benzpinacol, photoisomerization of stilbene, and the Norrish Type I and II reactions of carbon
Diel's-Alder and Gattermann Koch ReactionsPRUTHVIRAJ K
n organic chemistry, the Diels–Alder reaction is a chemical reaction between a conjugated diene and a substituted alkene, commonly termed the dienophile, to form a substituted cyclohexene derivative. It is the prototypical example of a pericyclic reaction with a concerted mechanism
The document outlines a proposed synthesis of N-alkenylated 2-pyridone containing isoquinoline alkaloids. The approach involves installing an aryl bromide via Suzuki coupling, followed by an asymmetric reduction of the tetrasubstituted alkene and a final Heck coupling to form the isoquinoline ring system. While initial attempts to reduce the alkene under achiral conditions showed trace amounts of the desired product by NMR, further optimization is needed to isolate it. Previous work established methods for synthesizing β-iodo-N-alkenyl 2-pyridones, which could then undergo Suzuki couplings to install various aryl groups for constructing the target alkaloids.
Carbon−Heteroatom Coupling Using Pd-PEPPSI Complexes (1)DrMAdamSayah
This document summarizes recent advances in using Pd-PEPPSI complexes as catalysts for aryl amination and aryl sulfination reactions. Pd-PEPPSI-IPent was found to be an effective catalyst for aryl sulfinations, enabling the reactions to proceed at 40°C. Further modifications to the pyridine and NHC ligands lowered the activation temperature of the precatalyst to as low as 40°C, allowing the aryl sulfinations to be carried out under very mild conditions. The improved steric environment around Pd is believed to facilitate the initial reductive elimination step needed to generate active Pd(0) and enter the catalytic cycle.
Location of functional groups & molecular stereochemistryNilesh Thorat
The document discusses various spectroscopic and chemical methods for determining the location of functional groups, molecular stereochemistry, and absolute stereochemistry in natural products. NMR and IR spectroscopy provide information on functional groups and their relationships. Chemical methods like oxidation, ozonolysis, ring formation reactions, and reaction with acids can reveal functional group positions and relationships. Absolute stereochemistry can be determined using methods like molecular rotation differences, asymmetric induction, optical rotation dispersion and circular dichroism, NMR techniques, and X-ray crystallography.
The document discusses haloalkanes and haloarenes. It provides information on:
- Physical properties of haloalkanes such as solubility, melting/boiling points, and polarity.
- Nucleophilic substitution reactions (SN1 and SN2) of haloalkanes including factors affecting the reactions.
- Elimination reactions (E1, E2, E1cb) of haloalkanes including factors affecting the reactions.
- Methods of preparation of haloalkanes such as halogenation of alkanes, hydrohalogenation of alkenes, and from alcohols.
What is a Heterocyclic Compound?
A heterocyclic compound has at least two different elements as a member of its ring.
The most common hetero atoms found on a cyclic ring are Oxygen (O), Nitrogen (N) and Sulphur (S).
Example:
Nucleic Acid that is present in the body responsible for storing and expressing genetic information, is an example of a Heterocyclic compound.
Essential micronutrient, Vitamins is also an example of a heterocyclic compound.
The majority of drugs, pesticides, dyes, and plastics are examples of heterocyclic compounds.
Classification of Heterocyclic Compounds
Based on the electronic arrangement, we can classify Heterocyclic compounds into two types:
Aliphatic Heterocyclic Compounds
Aromatic Heterocyclic Compounds
Aliphatic Heterocyclic Compounds
Aliphatic heterocyclic compounds are those cyclic heterocycles that do not contain any double bond.
The properties of aliphatic heterocyclic compounds are mainly affected due to ring strain.
Examples of aliphatic heterocyclic compounds are Aziridine, Ethylene Oxide, Thiirane, Oxetane, Azetidine, Thietane, Tetrahydrofuran (THF), Dioxane, Pyrrolidine, Piperidine, etc.
Aromatic Heterocyclic Compound
Aromatic heterocyclic compounds, as the name suggests, are cyclic aromatic compounds.
Aromatic Heterocyclic compounds obey Huckels Rule, i.e.
It should be cyclic.
It should be planar.
It should not contain any sp3 hybridised atoms.
It must have (4n+2) 𝛑 electrons.
Aromatic Heterocyclic compounds are analogous to Benzene.
Examples: Furan, Pyrrole, Thiophene, Indole, Benzofuran, Carbazole, Quinoline, Isoquinoline, Imidazole, Oxazole, Pyrazole, Pyridazine, Pyrimidine, Purine, etc.
Based on structure, we can classify Heterocyclic compounds into five types:
Three-Membered Heterocyclic Compounds
Four-Membered Heterocyclic Compounds
Five-Membered Heterocyclic Compounds
Six-Membered Heterocyclic Compounds
Condensed or Fused Heterocyclic Compounds
Three-Membered Heterocyclic Compounds
These heterocyclic compounds contain three atoms which may be saturated or unsaturated.
Based on the number of heteroatoms present, we can further classify them into two categories:
A green synthesis of isatoic anhydrides from isatins with urea–hydrogen perox...fer18400
The document describes a green synthesis method for producing isatoic anhydrides from isatins using urea-hydrogen peroxide complex and ultrasound irradiation. Four reaction procedures were tested using urea-hydrogen peroxide as the oxidizing agent and sulfuric acid as a catalyst. The procedures used either acetic anhydride/acetic acid or formic acid as solvents. Ultrasound irradiation was found to dramatically reduce reaction times from 2-24 hours down to 20-135 minutes. The method provides isatoic anhydrides in good yields and with high purity under mild conditions. Combining formic acid and ultrasound yielded the best results for most isatins tested.
Organic Chemistry Name Reaction with mechanisms 140TusharRanjanNath
140 name reactions in brief. Its mechanisms and advantages and disadvantages. All structures were made by individuals without pasting from other sources.
This document discusses nitrogen cycling and chemistry, including environmental forms of nitrogen and natural transformations of nitrogen in the environment. It covers the following key points:
- Nitrogen exists in numerous oxidation states ranging from -3 to +5 in the environment. Total nitrogen includes all nitrogen species while reactive nitrogen includes species that can undergo transformations.
- Natural nitrogen transformations include nitrogen fixation by lightning or specialized organisms, nitrification of ammonium to nitrate, and denitrification of nitrate back to nitrogen gas.
- Speciation diagrams can be used to predict nitrogen species based on redox potential and pH conditions. Increased anthropogenic nitrogen from sources like the Haber-Bosch process and fossil fuel combustion has altered the global
Serviced Apartment Ho Chi Minh For RentalGVRenting
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BEST FARMLAND FOR SALE | FARM PLOTS NEAR BANGALORE | KANAKAPURA | CHICKKABALP...knox groups real estate
welcome to knox groups real estate company in Bangalore. best farm land for sale near Bangalore and madhugiri . Managed farmland near Kanakapura and Chickkabalapur get know more details about the projects .Knox groups is a leading real estate company dedicated to helping individuals and businesses navigate the dynamic real estate market. With our extensive knowledge, experience, and commitment to excellence, we deliver exceptional results for our clients. Discover the perfect foundation for your agricultural aspirations with KNOX Groups' prime farm lands. These aren't just plots; they're the fertile grounds where vibrant crops flourish, livestock thrives, and unique agricultural ventures come to life. At KNOX, we go beyond selling land we curate sustainable ecosystems, ensuring that your journey toward agricultural success is seamless and prosperous.
1,4- Addition of copper acetylides to unsaturated ketonesSaibalendu Sarkar
TMSI promoted 1,4-addition of Copper acetylides to unsaturated aldehydes and ketones.This ppt is totally based on a paper published in Journal of American Chemical Society. The ppt is more about the analysis of the paper
This document provides an overview of 9 organic reactions: 1) Metal hydride reduction using NaBH4 and LiAlH4, 2) Clemmensen reduction, 3) Birch reduction, 4) Wolff-Kishner reaction, 5) Oppenauer oxidation, 6) Dakin reaction, 7) Beckmann rearrangement, 8) Schmidt rearrangement, and 9) Claisen-Schmidt condensation. For each reaction, it discusses the reaction mechanism, modifications, and applications in organic synthesis and drug development. The document serves as a reference for graduate students and researchers on important carbonyl reactions and their uses in pharmaceutical chemistry.
The document discusses various methods for forming C=C double bonds, including aldol condensation, Wittig reaction, Peterson olefination, and Julia-Lythgoe olefination. It also covers carbonyl coupling reactions, Tebbe reagent, Shapiro and related reactions, eliminations, conversions of diols and epoxides to olefins, and transformations of acetylenes and existing olefins. Specific examples and reaction conditions are provided for many of these C=C bond forming methods.
Photochemistry of carbony compounds.pptxssuserb017d1
- Carbonyl compounds absorb UV light at wavelengths of 280, 195, 170, and 155 nm, with the 280 nm band being important for photochemistry. This absorption corresponds to an n-π* transition.
- Upon absorption of UV light, carbonyl compounds can undergo four types of reactions: α cleavage, β cleavage, hydrogen abstraction, and addition to carbon-carbon multiple bonds. α cleavage (Norrish type I reaction) is the most common.
- In the Norrish type I reaction, absorption of UV light leads to cleavage of the carbonyl carbon-α carbon bond, forming an acyl radical and an alkyl radical. These radicals can then undergo secondary reactions like decarbonylation or hydrogen abstraction.
This document describes an unprecedented C-methylation reaction at the 2-position of 4-chromanone-2-carboxylates using the Corey–Chaykovsky reagent (dimethylsulfoxonium methylide, DIMSOY). Treatment of various 4-chromanone-2-carboxylates with DIMSOY results in good yields of the corresponding 2-methylated products, rather than the expected epoxide formation. Computational calculations provide evidence that the reaction proceeds through cisoid addition of DIMSOY to the carbonyl, formation of a betaine intermediate, and methyl transfer to C2 via a transition state, enabled by the basic nature of DIMSO
Sulfonium-Ion Glycosidase Inhibitors and Their DerivativesAndeChennaiah
This document summarizes research on naturally occurring sulfonium-ion glycosidase inhibitors and their derivatives. It outlines the synthesis of several inhibitors including salacinol, kotalanol, and ponkoranol. Various analogs of these inhibitors were also synthesized to investigate structure-activity relationships. Enzyme inhibition studies showed that some analogs maintained similar inhibitory activity to the natural products, while others showed reduced or no activity. In conclusion, discoveries in this field of sulfonium-ion glycosidase inhibitors have increased in the last 20 years, with some molecules considered as potential diabetes therapeutics. However, the area remains young with opportunities for chemists to develop novel inhibitors.
This document discusses ozone chemistry and the Wittig reaction. It describes the mechanism of ozone addition to double bonds, forming primary and secondary ozonides. The key intermediate in the mechanism is the zwitterion. It also discusses using nucleophilic reduction of secondary ozonides to form carbonyl compounds such as aldehydes and ketones. The Wittig reaction involves using ylides derived from phosphonium salts to displace oxygen from ozonides. This project investigated the cis/trans isomerism and solvent effects of Wittig reactions using three different ylides and solvents in one-flask syntheses of cinnamonitrile, benzylidene succinic anhydride, and methyl cinnamate
This document discusses metathesis reactions and their applications in organic synthesis. It begins with definitions and examples of different types of metathesis reactions including alkene, alkyne, and enyne metathesis. It then covers the key catalysts used, such as Grubbs and Schrock catalysts, as well as the 2005 Nobel Prize awarded for the development of metathesis reactions. The document concludes by outlining several important applications of metathesis in synthesizing biologically active compounds and natural products.
Crown ethers
NOMENCLATURE
GENERAL SYNTHESIS OF CROWN ETHER
AZA CROWN
CRYPTAND
APPLICATIONS
1. SYNTHETIC APPLICTION
Esterification
Saponification
Anhydride formation
Potassium permanganate oxidation
Aromatic substitution reactions
Elimination reactions
Displacement reaction
Generation of carbenes
Superoxide anion
Alkylations – 1. o-alkylations
2. c-alkylations
3. n-alkylations
2. ANALYTICAL APPLICATION
Determination of gold in geological samples
Super critical fluid extraction of trace metal from solid and liquid materials
Application of ionic liquids in analytical chemistry
Oxidation and determination of aldehydes
Crown ethers are used in the laboratory as phase transfer catalyst
OTHER APPLICATION
It is used in photocynation
Resolution of racemic mixture
Benzoin condensation
Hetrocyclisation
Synthesis of furanones
Acetylation of secondary amines in presence of primary amine
The document discusses the synthesis of heterobimetallic NHC ligand based complexes and their catalytic applications. It describes various methods for synthesizing these complexes using triazolylidene and imidazolylidene ligands to link two metal centers. Testing of the complexes showed that combining two metals into a single ligand framework often provides better catalytic performance than using a mixture of homometallic complexes. The binding site of the metals, whether as N^N chelate or NHC, was also found to influence catalytic activity.
This document summarizes a seminar on photochemistry presented to the Department of Chemistry Post Graduation Center. The seminar covered various types of photochemical reactions including photoreduction, photoisomerization, photochemical substitution, photodimerization, and photolysis of carbonyl compounds. Photochemistry involves chemical reactions that are initiated by the absorption of light, most commonly in the visible or ultraviolet regions. A variety of reaction types such as reduction, synthesis, and isomerization can be induced photochemically. Examples of specific photochemical reactions discussed include the reduction of benzophenone to benzpinacol, photoisomerization of stilbene, and the Norrish Type I and II reactions of carbon
Diel's-Alder and Gattermann Koch ReactionsPRUTHVIRAJ K
n organic chemistry, the Diels–Alder reaction is a chemical reaction between a conjugated diene and a substituted alkene, commonly termed the dienophile, to form a substituted cyclohexene derivative. It is the prototypical example of a pericyclic reaction with a concerted mechanism
The document outlines a proposed synthesis of N-alkenylated 2-pyridone containing isoquinoline alkaloids. The approach involves installing an aryl bromide via Suzuki coupling, followed by an asymmetric reduction of the tetrasubstituted alkene and a final Heck coupling to form the isoquinoline ring system. While initial attempts to reduce the alkene under achiral conditions showed trace amounts of the desired product by NMR, further optimization is needed to isolate it. Previous work established methods for synthesizing β-iodo-N-alkenyl 2-pyridones, which could then undergo Suzuki couplings to install various aryl groups for constructing the target alkaloids.
Carbon−Heteroatom Coupling Using Pd-PEPPSI Complexes (1)DrMAdamSayah
This document summarizes recent advances in using Pd-PEPPSI complexes as catalysts for aryl amination and aryl sulfination reactions. Pd-PEPPSI-IPent was found to be an effective catalyst for aryl sulfinations, enabling the reactions to proceed at 40°C. Further modifications to the pyridine and NHC ligands lowered the activation temperature of the precatalyst to as low as 40°C, allowing the aryl sulfinations to be carried out under very mild conditions. The improved steric environment around Pd is believed to facilitate the initial reductive elimination step needed to generate active Pd(0) and enter the catalytic cycle.
Location of functional groups & molecular stereochemistryNilesh Thorat
The document discusses various spectroscopic and chemical methods for determining the location of functional groups, molecular stereochemistry, and absolute stereochemistry in natural products. NMR and IR spectroscopy provide information on functional groups and their relationships. Chemical methods like oxidation, ozonolysis, ring formation reactions, and reaction with acids can reveal functional group positions and relationships. Absolute stereochemistry can be determined using methods like molecular rotation differences, asymmetric induction, optical rotation dispersion and circular dichroism, NMR techniques, and X-ray crystallography.
The document discusses haloalkanes and haloarenes. It provides information on:
- Physical properties of haloalkanes such as solubility, melting/boiling points, and polarity.
- Nucleophilic substitution reactions (SN1 and SN2) of haloalkanes including factors affecting the reactions.
- Elimination reactions (E1, E2, E1cb) of haloalkanes including factors affecting the reactions.
- Methods of preparation of haloalkanes such as halogenation of alkanes, hydrohalogenation of alkenes, and from alcohols.
What is a Heterocyclic Compound?
A heterocyclic compound has at least two different elements as a member of its ring.
The most common hetero atoms found on a cyclic ring are Oxygen (O), Nitrogen (N) and Sulphur (S).
Example:
Nucleic Acid that is present in the body responsible for storing and expressing genetic information, is an example of a Heterocyclic compound.
Essential micronutrient, Vitamins is also an example of a heterocyclic compound.
The majority of drugs, pesticides, dyes, and plastics are examples of heterocyclic compounds.
Classification of Heterocyclic Compounds
Based on the electronic arrangement, we can classify Heterocyclic compounds into two types:
Aliphatic Heterocyclic Compounds
Aromatic Heterocyclic Compounds
Aliphatic Heterocyclic Compounds
Aliphatic heterocyclic compounds are those cyclic heterocycles that do not contain any double bond.
The properties of aliphatic heterocyclic compounds are mainly affected due to ring strain.
Examples of aliphatic heterocyclic compounds are Aziridine, Ethylene Oxide, Thiirane, Oxetane, Azetidine, Thietane, Tetrahydrofuran (THF), Dioxane, Pyrrolidine, Piperidine, etc.
Aromatic Heterocyclic Compound
Aromatic heterocyclic compounds, as the name suggests, are cyclic aromatic compounds.
Aromatic Heterocyclic compounds obey Huckels Rule, i.e.
It should be cyclic.
It should be planar.
It should not contain any sp3 hybridised atoms.
It must have (4n+2) 𝛑 electrons.
Aromatic Heterocyclic compounds are analogous to Benzene.
Examples: Furan, Pyrrole, Thiophene, Indole, Benzofuran, Carbazole, Quinoline, Isoquinoline, Imidazole, Oxazole, Pyrazole, Pyridazine, Pyrimidine, Purine, etc.
Based on structure, we can classify Heterocyclic compounds into five types:
Three-Membered Heterocyclic Compounds
Four-Membered Heterocyclic Compounds
Five-Membered Heterocyclic Compounds
Six-Membered Heterocyclic Compounds
Condensed or Fused Heterocyclic Compounds
Three-Membered Heterocyclic Compounds
These heterocyclic compounds contain three atoms which may be saturated or unsaturated.
Based on the number of heteroatoms present, we can further classify them into two categories:
A green synthesis of isatoic anhydrides from isatins with urea–hydrogen perox...fer18400
The document describes a green synthesis method for producing isatoic anhydrides from isatins using urea-hydrogen peroxide complex and ultrasound irradiation. Four reaction procedures were tested using urea-hydrogen peroxide as the oxidizing agent and sulfuric acid as a catalyst. The procedures used either acetic anhydride/acetic acid or formic acid as solvents. Ultrasound irradiation was found to dramatically reduce reaction times from 2-24 hours down to 20-135 minutes. The method provides isatoic anhydrides in good yields and with high purity under mild conditions. Combining formic acid and ultrasound yielded the best results for most isatins tested.
Organic Chemistry Name Reaction with mechanisms 140TusharRanjanNath
140 name reactions in brief. Its mechanisms and advantages and disadvantages. All structures were made by individuals without pasting from other sources.
This document discusses nitrogen cycling and chemistry, including environmental forms of nitrogen and natural transformations of nitrogen in the environment. It covers the following key points:
- Nitrogen exists in numerous oxidation states ranging from -3 to +5 in the environment. Total nitrogen includes all nitrogen species while reactive nitrogen includes species that can undergo transformations.
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Omalley_Jun_04.pdf
1. Group Meeting
6/9/2004
O'Malley Pyridine Synthesis: Cliff Notes
Note: Due to time constraints, this is not an exhaustive exploration of the myriad ways to create
substituted pyridines. This summary focuses on ring-construction reactions, rather than functionalization
of existing pyridine rings. Quinolines and Isoquinolines can be considered substituted pyridines; however
they possess their own rich chemistry and deserve their own summary. This review summarizes their
chemistry only insofar as it pertains to pyridine chemistry in general.
General approaches to pyridine rings:
Most synthses of pyridine rings rely upon one of two approaches: the condensation of carbonyl
compounds or cycloaddition reactions. There are exceptions, such as ring expansion from 5-membered
rings, but these approaches are generally low-yielding, narrow in applicability, or both.
Condensation approaches to pyridines:
1. Condensation of 1,5-dicarbonyls
Condensation of 2,3-ene-1,5-diones with ammonia is the simplest approach, but offers relatively
little simplification:
O O
H NH3
N
A somewhat simpler approach relies on condensation of 1,5 diones followed by oxidation
O O
H NH3
N
H
H
H
N
air, O2, HNO3
HNO2, CAN,
Cu(NO3)2, MnO2
The oxidation step can be avoided by using hydroxylamine instead of ammonia
O O
H NH2OH
N
OH
H
H
N
-H2O
Several variations on these themes have been developed, such as the use of dimethyl hydrazones
Kelly and Liu, JACS, 1985, 107, 4998-4999.
NNMe2 BuLi;
PhSCu;
O
N
82%
NNMe2 BuLi;
PhSCu;
O
AcCN; ; AcOH (reflux)
N
O
45%
Yields were generally acceptable
for enone procedure, low for acyl
cyanide procedure. Reaction
requires extended time.
;
;
AcOH (reflux)
2. Hantzsch Synthesis
Condensation of an aldehyde, two equivalents of a 1,3-dicarbonyl, and ammonia yields symmetrical
pyridines.
O
O H
O
O
O
N
H
Me O
O
N
Me O
O
NH3,
rt, 4 days
51%
NaNO2,
AcOH
83%
Modifications have been made to allow for synthesis of asymmetric pyridines, by performing one or
more of the condensation steps prior to the reaction.
Robinson et. al. J. Het. Chem. 1998, 35, 65.
X
Ph O O
Ph
R1
R2 N
Ph
X
Ph
R1
R2
NH4OAc
AcOH
O2
moderate to good yields for X = NO2,
NHAc, or CN, R1= H, Me, or CN, R2 = Ph,
Me, or 2-furyl
O
Ph
X
Ph
O R1
R2
+
+
NH4OAc
AcOH
O2 N
Ph
X R1
R2
alternate pathway improved yields for
some reactions, particularly X=CN
procedures have also been developed using enamine esters and enones
This procedure served as a key step in an elegant synthesis of the Rubrolone chromophore
Kelly et. al., Tet. Lett. 1986, 27, 6049-6050.
NNMe2
BuLi;
PhSCu;
NC C3H7
O
;
AcOH reflux
N
O
Me
nPr
31%
N
Me
nPr
O
O
O
OTBS
O
N
Me
nPr
O O
O
O
H
H
H
OTBS
N
Me
nPr
O O
MEMO
O
H
H
H
OTBS
N
Me
nPr
O O
O
MEMO
H
H
H
OTBS
MEMCl
38% (recycled) 46%
+
1. TBAF,
88%
2. HCl, air,
100%
N
O
HO
HO
O
nPr
Rubralone chromophore
N
O
HO
O
nPr
O
O
Me
HO
HO
H
HO
Rubralone
67%
2. Group Meeting
6/9/2004
O'Malley Pyridine Syntheses: Cliff Notes
The Bohlmann-Rahtz procedure served as a key step in the synthesis of the thiopeptide promothiocin A
Moody et. al. JACS, 2000, 122, 3301-3313
N
O
Me
NHBoc
EtO2C O
Me
N
O
Me
NHBoc
EtO2C
Me
NH2
N
O
Me
NHBoc
Me
N
EtO2C
NH4OAc
PhH, AcOH,
85%
OBn
O
BnO
EtOH, 50 °C;
140 °C, in vacuo,
83%
4. Synthesis from 1,3 dicarbonyls and 3-aminoenones
O
O H2N
O
N
O
+
Stork has developed a method of using isoxazoles as masked 3-amino-2-enones
Stork et. al. JOC. 1971, 36
N
O
ClH2C
Me
Me
Me
O O
Me
N
O
Me
Me
O
Me
O
Me
N
Me Me
O
Me
O
Me
K2CO3
61%
1. Pd-C. H2, 74%
2. [O]
+
3. Bohlmann-Rahtz Synthesis
R1 NH2 E
R2O2C
+
E= RCO or CN
EtOH
50 °C
R2O2C
O
R1
NH2
120-160 °C
N
R1
R2O2C
High temperatures in the dehydration step can be avoided by performing the condensation under
acidic conditions. Bagley et. al. Synlett, 2001, 1149-1151.
R1 NH2
R2
R4
O R3
N
R1
R2
R3
R4
AcOH or
amberlyst 15
50 °C
yields 65-95% for R1= Me or 2-furyl,
R2= EtO2C or tBuO2C R3= Me or CO2Et,
R4= Alkyl, Ph, H, or TMS
use of amberlyst 15 improved yields for R2= tBuO2C and R4 = Ph
5. Kröhnke annulation
Condensation of a-pyridinium methyl ketone salts and eneones that proceeds through a 2,3-ene-1,5-
dione
N
O
R1 N
R2
O
R2
Br
NH4OAc, AcOH R1
R2
R3
O O
N
F
I
NH4OAc
90 °C, 3 h
47%
N
F
(Malkov et. al. Tet. Lett. 2001, 42, 3045-3048)
1-cyanomethylpyridinium salts can also be used to give 2-aminopyridines
Kröhnke, Synthesis, 1976, 1-24.
N
CN
X
R1
R2
+
+
N
H2N
R3
R2
NH4OAc
AcOH
ca. 60%
Gives good yields for R= alkyl, aryl, or
alkenyl. R3= COOH gives somewhat lower
yields (40-80%).
CF3
R1
O
O
R2
H2N CH3
+
N
CF3
R2
CH3
R1
EtOH or MeCN
reflux
Gives 70-80% yield for R1= Me or aryl, R2 =
CO2Et or CN
When applied to quinolines, this is referred to as the Friedlander condensation. This procedure was used
by Danishefsky and Stork in their syntheses of Camptothecin. Danishefsky et. al. JACS, 1971, 93, 4074
Shibata, Synthesis, 1997, 13211-1324
N
CO2Me
O
CO2H
NH2
CHO
+
NaOH
N
CO2H
O
CO2H
N
+
O
O
3. Group Meeting
6/9/2004
O'Malley Pyridine Syntheses: Cliff Notes
Cycloaddition approaches to pyridines
1. Diels-Alder reactions with 1-azadienes
The most straightforeward cycloaddition approach to pyridines involves a Diels-Alder reaction of an
1-azadiene with an alkene or alkyne, followed by subsequent oxidation. However, this route is rarely
used, as the Diels-Alder reaction is disfavored on electronic, conformational, and thermodynamic
grounds. A modification of this approach uses an electron donating group on the nitrogen, which is
subsequently eliminated.
N
Me
NMe2
O
O
+
O
O
N
Me
1. ultrasound,
0.5 h 88%
2. air, 1 day, 92%
N
Me
NMe2
MeO2C CO2Me
neat, 50 °C, ultrasound, 50h;
CDCl3, reflux, 2h; air, 60% N
Me CO2Me
CO2Me
Villacampa et. al. Tetrahedron, 1994, 50, 10047-10054
This technique was used by Boger in his approach to the Rubrolone aglycon
Boger et. al. JACS, 2000, 122, 12169-12173.
O
N
OMe
Me
nPr N
O
Me
175 °C, 36 h
70%
nPr
2. Inverse electron demand Diels-Alder approaches
Because of the intransigence of 1-azadienes in [4+2] cycloadditions, the use of a variety of heterocyclic
azadienes in an inverse demand Diels-Alder reaction, followed by either extrusion of part of the resulting
bicycle in a retro-[4+2] reaction or scission of the resulting bridge has become the favored method for
constructing pyridine rings. (Boger, Chem. Rev., 1986, 86, 781-793.
Isozaxoles have been used for this reaction, but fragmentation of the oxo bridge can proceed by several
different pathways, complicating the reaction. Also, only isoxazoles with particular substitution patterns
undergo cycloaddition in productive yields. This reaction is called the Kondrat'eva synthesis.
N
O
Me
N
O
R1 R2
R1
R2
Me N N N
Me
R1
R2
Me
HO R2
Me
HO
R1
R2
(-H2O) (-HR1) (-H2)
not normally observed
The Kondrat'eva synthesis was used by Weinreb in his synthesis of Eupolauramine.
Weinreb et. al., JOC, 1984, 49, 4325-4339.
N O
CO2Me
N
CO2Me
DBN N
NMe
O
OMe
Eupolauramine
76%
Pyrimidines are also capable of serving as pyrrole precursors in a DA/Retro-DA sequence. The
regiochemistry of the resulting pyridine is dependent upon the dienophile and the substitution pattern of
the parent pyrimidine.
N N
N N
N N
CO2Et
CO2Et
EtO2C
NO2
Me NEt2
Me NEt2
MeO
MeO
N
N
N
N
N
N
CO2Et
NEt2
Me
EtO2C
CO2Et
NO2
MeO OMe
Me
Me
NEt2
Me
N
N
N
CO2Et
Et2N
Me
Et2N
Me
CO2Et
CO2Et
NO2
Me
OMe
90%
81%
Pyrimidines with two or three complementary electron donating groups are capable of undergoing
normal Diels-Alder reactions with activated dienophiles, although yields are moderate at best.
N N
Me2N OMe
NMe2
MeO2C CO2Me
N
Me2N
NMe2
CO2Me
CO2Me
70%
Pyrazines can also undergo inverse electron demand DA/retro DA cascades to give pyridines, although
this is less common.
N
N
CO2Me
Me NEt2
N
Me
NEt2
CO2CH3
-HCN
70%
4. Group Meeting
6/9/2004
O'Malley Pyridine Syntheses: Cliff Notes
1,2,4-triazenes readily undergo inverse demand Diels-Alder reaction with electron-rich dienophiles
with well-defined regioselectivity. This makes them attractive precursors to pyridines, as addition across
C-3/C-5 is favored for all dieneophiles, with the exception of some ynamines. The most popular version
of this reaction uses a pyrrolidine enamine or a ketone and pyrrolidine as the dienophile; this is called
the Boger pyridine synthesis.
N N
N
N
N
74%
N N
N Et
O
Et
H
N N
Et
Et
93%
There is a strong preference for the nucleophilic carbon of the dienophile to add to C-3 of the triazine.
This is reinforced by electron withdrawing substituents at C-3 or C-3, C-5, and C-6, but can be reversed
by electron withdrawing substituents at C-3 or C-3 and C-5. The presence of alkyl groups on the
dienophile or the use of a morpholino dienophile can degrade the extent of regioselectivity.
A convenient method for the generation of 1,2,4-triazines is via a Diels-Alder/Retro Diels-Alder sequence
involving a 1,2,4,5-tetrazine and a nitrogen-containing dienophile. This strategy was used by Boger in his
synthesis of Streptonigrin. (Boger and Panek, JOC, 1983, 48, 621-623, JACS, 1985, 107, 5745-5754.
N
NO2
MeO
NH
SCH3
N
N
N
N CO2Me
MeO2C
N
NO2
MeO
N
N
N CO2Me
MeO2C
Me
N
OBn
OMe
OMe
+
N
NO2
MeO
N CO2Me
MeO2C Me
OBn
OMe
OMe
80 °C, 22h, 82%
6.2 kbar, CH2Cl2,
rt, 120 h, 65%
2.8:1 regioselectivity
Kende intermediate
N
MeO
N CO2Me
MeO2C Me
OBn
OMe
OMe
O
O
H2N
streptonigrin
3. Co-catalyzed [2 + 2 + 2] cycloadditions
Reaction of excess acetylene with one equivalent of a nitrile and ca. 1 mol % of a cobalt catalyst, such
as CpCo(COD), leads to 2-substituted pyridines in good yield under conditions where an initial excess
of nitrile is present. However, when unsymmetrical acetylenes are used mixtures of regioisomeric
products are often obtained. Electron-poor nitriles do not work in this reaction. Bönneman, ACIEE,
1978, 17, 505-515
RCN
CpCo(COD),
120-130 °C
N
R
Yields are > 90% for R= alkyl, Ph, or Bn. R=
ethenyl
gives 78%. 100-600 turnovers per hour are
possible.
R1CN
CpCo(COD),
120-130 °C N
R1
N
R1
R2
R2
R2
+
R2
A B
Yields of 50-85%, A:B of
60:40 to 80:20 for R1, R2 =
alkyl, Ph, alkenyl
Problems of regioselectivity can be avoided by using diynes and nitriles or alkynyl nitriles and alkynes.
The less sterically hindered orientation of the product pyridine is greatly favored under these conditions.
Vollhardt, ACIEE, 1984, 23, 539-556.
BuCN
CpCo(CO)2
N N
Bu Bu
73% 4.1%
Vollhardt et. al. J. Chem. Soc. Chem. Comm. 1982, 133-134.
N
TMS
TMS
N
TMS
TMS
CpCo(CO)2
PhMe, reflux
light, 77%
Moderate to good yields for
5,6,7 membered rings, alkyl,
trialkylsilyl, ester substituents
on alkyne.
Heteroatoms are tolerated in the linking chain, but N and S can interfere with catalyst turnover. This
served as the basis of Vollhardt's synthesis of vitamin B6. Parnell and Vollhardt, Tetrahedron, 1985, 41,
5791-5796.
O
SnMe3
SnMe3
MeCN
CpCo(CO)2,
xylene, reflux,
light, 48 h; Al2O3
44%
N
O
Me
SnMe3
N
O
Me
I
I2
99%
NaOMe
CuI2, 37%
N
O
Me
OMe
1. HBr, 78%
2. H2O, reflux;
AgCl, 68%
NH
Me
OH
HO
HO
Cl
Vitamin B6
cat.
R2
5. Group Meeting
6/9/2004
O'Malley Pyridine Syntheses: Cliff Notes
4. Electrocyclization of polyunsaturated imines or oximes
Reinhoudt and co-workers cyclized unsaturated oximes generated from cyclic nitrones to pyridines
in moderate yield. (Reinhoudt et. al., Tetrahedron, 1989, 45, 3131-3138.
NO2
R1
R2
NEt2
R3 N
O
R1
R2
CONEt2
R3
rt, 30-60%
KOtBu
60-85%
N
R1 (R3)
R2
CONEt2
(R3)
R1= Alkyl or Ph, R2= Ar, R3= Ph or alkenyl
Katsumura and co-workers used two distinct electrocyclizations in their approach to the ocular age
pigment A2-E. Katsumura et. al. JOC, 2001, 66, 3099-3110.
TBSO
CO2Et
CHO
N CO2Et
TBSO
NH2OH•HCl;
AcCl,py., 53%
TBSO
CO2Et
CHO
N CO2Et
TBSO
1. LHMDS
2. DDQ
How Medicinal Chemists Do It
Lee et. al. J. Med. Chem. 2001, 44, 2133-2138.
N
N
NH2
NH2
R
CHO
NMe2
+ N
N
NH2
N
R
NMe2
N
N
NH2
N
R
NMe2
Br
CN
CN
N N
O
O
+
"a"
N N
N
NC
H2N
Br
O