Finishing off the reactions of carboxylic acid derivatives (well the substitution reactions) and introducing oxidation and reduction. Then looking at the oxidation of alkenes (epoxidation and dihydroxylation) and alcohols (the usual suspects).
Lecture 6: C-C bond formation
The big one; the all important formation of C-C bonds. Reagents include organometallics and enolates. There will also be a slight detour into the wonderful world of pKa.
Told you that this was the important one. This weeks reagents include more enolates and then reactions with the C=O group including the such classics as the Wittig reaction.
This document discusses functional group interconversions, specifically focusing on sulfonate esters. It provides information on common sulfonate leaving groups like tosyl, mesyl, and triflate groups and their relative reactivities. It also discusses the mechanisms and standard methods for preparing sulfonate esters from alcohols using these strong acidic leaving groups, noting that pyridine cannot deprotonate an alcohol directly due to pKa differences.
Finishing oxidation by looking at the Baeyer-Villiger reaction and then turning our attention to reduction. Once again we will see the usual suspects with a who is who of hydride sources.
The document provides information about various carbon-carbon bond forming reactions including the aldol reaction, Claisen condensation, Dieckmann cyclization, Robinson annulation, and the Hajos-Parrish-Eder-Sauer-Wiechert reaction. It discusses how to control the chemoselectivity of reactions and outlines strategies like choosing the correct nucleophile or pre-forming enolates. Functional groups in specific arrangements like a 1,3-diol relationship indicate certain reaction types. The key message is that retrosynthesis involves recognizing underlying patterns in molecular structures.
The big topic of the last few years, the use of small organic molecules to catalyse enantioselective transformations. This lecture will start with proline before moving on to some of MacMillan's contributions to this field and, finally, finish with hydrogen bond catalysts and Brønsted acids.
The document summarizes the retrosynthetic analysis and total synthesis of the natural product callipeltoside C. The retrosynthesis breaks the molecule down into 3 main fragments - the sugar portion, middle section, and bottom half. The synthesis proceeds by synthesizing each fragment separately and coupling them together, with the sugar portion requiring the most steps due to protecting group manipulation and diastereoselective transformations. The total synthesis takes 18 linear steps to assemble all the fragments and achieve the target natural product.
Lecture 6: C-C bond formation
The big one; the all important formation of C-C bonds. Reagents include organometallics and enolates. There will also be a slight detour into the wonderful world of pKa.
Told you that this was the important one. This weeks reagents include more enolates and then reactions with the C=O group including the such classics as the Wittig reaction.
This document discusses functional group interconversions, specifically focusing on sulfonate esters. It provides information on common sulfonate leaving groups like tosyl, mesyl, and triflate groups and their relative reactivities. It also discusses the mechanisms and standard methods for preparing sulfonate esters from alcohols using these strong acidic leaving groups, noting that pyridine cannot deprotonate an alcohol directly due to pKa differences.
Finishing oxidation by looking at the Baeyer-Villiger reaction and then turning our attention to reduction. Once again we will see the usual suspects with a who is who of hydride sources.
The document provides information about various carbon-carbon bond forming reactions including the aldol reaction, Claisen condensation, Dieckmann cyclization, Robinson annulation, and the Hajos-Parrish-Eder-Sauer-Wiechert reaction. It discusses how to control the chemoselectivity of reactions and outlines strategies like choosing the correct nucleophile or pre-forming enolates. Functional groups in specific arrangements like a 1,3-diol relationship indicate certain reaction types. The key message is that retrosynthesis involves recognizing underlying patterns in molecular structures.
The big topic of the last few years, the use of small organic molecules to catalyse enantioselective transformations. This lecture will start with proline before moving on to some of MacMillan's contributions to this field and, finally, finish with hydrogen bond catalysts and Brønsted acids.
The document summarizes the retrosynthetic analysis and total synthesis of the natural product callipeltoside C. The retrosynthesis breaks the molecule down into 3 main fragments - the sugar portion, middle section, and bottom half. The synthesis proceeds by synthesizing each fragment separately and coupling them together, with the sugar portion requiring the most steps due to protecting group manipulation and diastereoselective transformations. The total synthesis takes 18 linear steps to assemble all the fragments and achieve the target natural product.
Self explanatory really, this lecture looks at chiral auxiliaries. We will concentrate on oxazolidinones in alkylations, aldol reaction and the Diels-Alder reaction. There will be a couple examples of other auxiliaries.
This is the biggy, the one everyone wants to achieve. Here we will be looking at metal-based chiral catalysis. We will concentrate on bisoxazoline-based Lewis acid catalysis and then look at reductions before finishing with the ubiquitous Sharpless epoxidation and dihydroxylation.
A look at epothilone A as it includes examples of many different forms of asymmetric synthesis. Also includes a little bit about ring-closing metathesis.
This document provides a summary of dienes and alkynes. It discusses resonance stabilization of conjugated dienes and their regioisomers when undergoing electrophilic addition. For alkynes, it covers their lack of acidity due to their sp hybridization and decreasing acid strength. It also summarizes the hydration of alkynes, which proceeds by a Markovnikov addition through a mercurinium ion intermediate and tautomerizes to the enol form.
The document discusses the concept of substrate control in directed epoxidation reactions. It shows that when performing epoxidation reactions on substrates containing multiple oxidizable positions, the reaction preferentially forms epoxides at positions that minimize 1,3-allylic strain. Substrate control allows for high regioselectivity in epoxidation based on sterics and substrate conformation. Directed epoxidation reactions can achieve up to 99:1 regioselectivity through substrate control and transition state stabilization.
Use of stoichiometric amounts of a chiral source. The usual suspects will be discussed, including borane reagents (mostly pinene derivatives) and the Brown allylation.
Gives an introduction to total synthesis and why we do it (which reminds me, I must add a picture of Everest, as I think the fact that 'it is there' is the main reason for most syntheses). Then to introduce the topic with a reasonably simple synthesis, we will look at an example of the synthesis of Tamiflu.
Proteins are composed of amino acids linked together by peptide bonds. There are 20 standard amino acids that make up proteins. Amino acids have different properties depending on their side chains, which can be nonpolar, polar, acidic, or basic. When amino acids join together via peptide bonds, they form the primary structure of proteins. The peptide bond is planar and rigid, giving proteins their distinctive 3D structures.
This document summarizes the optimization of an organocatalytic domino Michael-Aldol reaction to synthesize bispirooxindoles. Various cinchona alkaloid derivatives were evaluated as catalysts, with a trifunctional S-binaphthyl diamine catalyst (VIII) giving excellent diastereoselectivity and enantioselectivity. Reaction conditions such as temperature, solvent, and substrate scope were varied, demonstrating good yields and selectivity for a range of substrates. A different protecting group was also investigated, and bispirooxindoles were successfully deprotected to give the corresponding amines in high yields and selectivity.
The lecture discusses the mechanisms of ozonolysis and radical addition reactions to alkenes. Ozonolysis involves a three step mechanism where ozone cleaves the alkene to form an ozonide intermediate which then decomposes to a carbonyl compound. Radical addition reactions involve a three step chain reaction mechanism of initiation, propagation, and termination. The stability of radical intermediates is influenced by resonance stabilization, which explains why styrene reacts with HBr to give a single, benzylic bromide product.
This document describes the synthesis of [2.2.1]bicyclo-1,4-bisoxaoline ligands using diastereoselective alkylation reactions. The synthesis starts with esterification of the carboxylic acid groups, followed by alkylation with ethyl aluminum chloride to form the (R,R) and (S,S) ligands in high diastereomeric excess. The ligands are then functionalized through reactions with thionyl chloride and amines to introduce various substituents at R1. Deprotection yields the final ligands with defined stereochemistry and substituents at the backbone, sidechain, and R1 position.
The document provides an overview of chemical reactions, including:
1) It describes three main types of chemical reactions: substitution reactions, addition reactions, and elimination reactions.
2) It explains that nucleophiles are electron-rich reagents that donate electrons, while electrophiles are electron-poor reagents that accept electrons. Common nucleophiles include anions and molecules with lone pairs, while common electrophiles include protons and elements in Group 13.
3) Using examples, it illustrates how nucleophiles can donate electrons in substitution and addition reactions, and how electrophiles can accept electrons in these reactions.
The document summarizes the chemistry of azoxy compounds, which contain the azoxy functional group. Azoxyalkanes are generally very stable to heat and light and do not readily undergo reactions like loss of nitrogen. However, intramolecular radical reactions of azoxy compounds can generate cyclic aminyl nitroxides or hydrazyls. The azoxy group stabilizes attached carbon-centered radicals, but the chemistry of α-azoxy radicals is not fully understood. Thermolysis of azoxy compounds usually does not lead to loss of nitrogen dioxide, and instead forms amine oxides or stabilized radicals through rearrangement.
The Mannich reaction involves the condensation of an enolizable carbonyl compound, an aldehyde such as formaldehyde, and a primary or secondary amine. This results in an aminoalkylation and formation of a β-aminocarbonyl compound known as a Mannich base. Modifications using preformed Mannich bases and reactive substrates extend the scope and selectivity of the reaction. The Mannich reaction has wide applications in organic synthesis and for producing natural and medicinal compounds.
The Mitsunobu reaction allows the conversion of alcohols to various functional groups using trialkyl/triaryl phosphine and dialkyl azodicarboxylate reagents. It proceeds via an oxidation-reduction mechanism. Common applications include esterification, etherification, and N-alkylation reactions. Recent advances have focused on replacing conventional reagents to improve selectivity and yields. The Mitsunobu reaction has been widely used in the synthesis of natural products and pharmaceuticals.
This document provides an overview of conducting polymers, focusing on synthetic strategies for electron-conducting polymers. The main types of conducting polymers are introduced as electron-conducting, proton-conducting, and ion-conducting. Poly(acetylene) is discussed as the simplest conjugated polymer, with early synthesis routes producing insoluble powders and later routes enabling the production of processable films. Other discussed electron-conducting polymers include poly(diacetylene), poly(phenylene), and poly(thiophene). Precursor routes are described as an important method for obtaining processable poly(acetylene) with controlled morphology and improved properties over early synthesis methods.
The document discusses the synthetic, analytical, and therapeutic aspects of the pyrazole heterocyclic nucleus. Pyrazole rings are found in many pharmaceutical drugs due to their ease of preparation and important biological activities. Some key points:
- Pyrazoles have anti-inflammatory, antipyretic, antimicrobial, anticancer, and other therapeutic properties.
- They contain an NH group that allows for hydrogen bonding and complex formation.
- Reduction or oxidation at nitrogen atoms in the ring can yield derivative structures.
- Many established drug molecules contain the pyrazole nucleus, including celecoxib, phenylbutazone, and apixaban.
Global Strategy for Asthma Management and Prevention Updated 2009 provides guidelines for diagnosing, treating, and managing asthma. It summarizes the burden of asthma worldwide and factors influencing asthma development. Guidelines are provided for classifying asthma and assessing control. A partnership approach between doctors and patients is emphasized. Treatment involves classifying severity and controlling asthma with medications and reducing exposures. Progress is monitored regularly to maintain control.
1) The document summarizes key information about penicillin, including its discovery by Alexander Fleming in 1928, its mechanism of action inhibiting bacterial cell wall synthesis, its classification into natural, resistant, aminopenicillin, and extended-spectrum types, and its common uses treating bacterial infections like pneumonia, meningitis, and strep throat.
2) The structural activity relationship of penicillin is discussed, noting essential components like the beta-lactam and thiazolidine rings and how substitutions at different positions can impact stability and activity.
3) Potential adverse effects are outlined, ranging from diarrhea to rashes to confusion, as well as therapeutic uses for treating various bacterial infections.
This document outlines the contents of a book on functional group interconversions. It covers topics like alcohols, carboxylic acids and their derivatives, oxidation and reduction reactions, and C-C bond formation. Each chapter explains different reaction types and transformation pathways. The introduction discusses using natural products for medical treatments historically and the importance of functional group interconversions in organic synthesis.
General introduction to the course followed by a basic introduction to asymmetric or stereoselective Synthesis. Then starting the course proper by looking at substrate control.
Self explanatory really, this lecture looks at chiral auxiliaries. We will concentrate on oxazolidinones in alkylations, aldol reaction and the Diels-Alder reaction. There will be a couple examples of other auxiliaries.
This is the biggy, the one everyone wants to achieve. Here we will be looking at metal-based chiral catalysis. We will concentrate on bisoxazoline-based Lewis acid catalysis and then look at reductions before finishing with the ubiquitous Sharpless epoxidation and dihydroxylation.
A look at epothilone A as it includes examples of many different forms of asymmetric synthesis. Also includes a little bit about ring-closing metathesis.
This document provides a summary of dienes and alkynes. It discusses resonance stabilization of conjugated dienes and their regioisomers when undergoing electrophilic addition. For alkynes, it covers their lack of acidity due to their sp hybridization and decreasing acid strength. It also summarizes the hydration of alkynes, which proceeds by a Markovnikov addition through a mercurinium ion intermediate and tautomerizes to the enol form.
The document discusses the concept of substrate control in directed epoxidation reactions. It shows that when performing epoxidation reactions on substrates containing multiple oxidizable positions, the reaction preferentially forms epoxides at positions that minimize 1,3-allylic strain. Substrate control allows for high regioselectivity in epoxidation based on sterics and substrate conformation. Directed epoxidation reactions can achieve up to 99:1 regioselectivity through substrate control and transition state stabilization.
Use of stoichiometric amounts of a chiral source. The usual suspects will be discussed, including borane reagents (mostly pinene derivatives) and the Brown allylation.
Gives an introduction to total synthesis and why we do it (which reminds me, I must add a picture of Everest, as I think the fact that 'it is there' is the main reason for most syntheses). Then to introduce the topic with a reasonably simple synthesis, we will look at an example of the synthesis of Tamiflu.
Proteins are composed of amino acids linked together by peptide bonds. There are 20 standard amino acids that make up proteins. Amino acids have different properties depending on their side chains, which can be nonpolar, polar, acidic, or basic. When amino acids join together via peptide bonds, they form the primary structure of proteins. The peptide bond is planar and rigid, giving proteins their distinctive 3D structures.
This document summarizes the optimization of an organocatalytic domino Michael-Aldol reaction to synthesize bispirooxindoles. Various cinchona alkaloid derivatives were evaluated as catalysts, with a trifunctional S-binaphthyl diamine catalyst (VIII) giving excellent diastereoselectivity and enantioselectivity. Reaction conditions such as temperature, solvent, and substrate scope were varied, demonstrating good yields and selectivity for a range of substrates. A different protecting group was also investigated, and bispirooxindoles were successfully deprotected to give the corresponding amines in high yields and selectivity.
The lecture discusses the mechanisms of ozonolysis and radical addition reactions to alkenes. Ozonolysis involves a three step mechanism where ozone cleaves the alkene to form an ozonide intermediate which then decomposes to a carbonyl compound. Radical addition reactions involve a three step chain reaction mechanism of initiation, propagation, and termination. The stability of radical intermediates is influenced by resonance stabilization, which explains why styrene reacts with HBr to give a single, benzylic bromide product.
This document describes the synthesis of [2.2.1]bicyclo-1,4-bisoxaoline ligands using diastereoselective alkylation reactions. The synthesis starts with esterification of the carboxylic acid groups, followed by alkylation with ethyl aluminum chloride to form the (R,R) and (S,S) ligands in high diastereomeric excess. The ligands are then functionalized through reactions with thionyl chloride and amines to introduce various substituents at R1. Deprotection yields the final ligands with defined stereochemistry and substituents at the backbone, sidechain, and R1 position.
The document provides an overview of chemical reactions, including:
1) It describes three main types of chemical reactions: substitution reactions, addition reactions, and elimination reactions.
2) It explains that nucleophiles are electron-rich reagents that donate electrons, while electrophiles are electron-poor reagents that accept electrons. Common nucleophiles include anions and molecules with lone pairs, while common electrophiles include protons and elements in Group 13.
3) Using examples, it illustrates how nucleophiles can donate electrons in substitution and addition reactions, and how electrophiles can accept electrons in these reactions.
The document summarizes the chemistry of azoxy compounds, which contain the azoxy functional group. Azoxyalkanes are generally very stable to heat and light and do not readily undergo reactions like loss of nitrogen. However, intramolecular radical reactions of azoxy compounds can generate cyclic aminyl nitroxides or hydrazyls. The azoxy group stabilizes attached carbon-centered radicals, but the chemistry of α-azoxy radicals is not fully understood. Thermolysis of azoxy compounds usually does not lead to loss of nitrogen dioxide, and instead forms amine oxides or stabilized radicals through rearrangement.
The Mannich reaction involves the condensation of an enolizable carbonyl compound, an aldehyde such as formaldehyde, and a primary or secondary amine. This results in an aminoalkylation and formation of a β-aminocarbonyl compound known as a Mannich base. Modifications using preformed Mannich bases and reactive substrates extend the scope and selectivity of the reaction. The Mannich reaction has wide applications in organic synthesis and for producing natural and medicinal compounds.
The Mitsunobu reaction allows the conversion of alcohols to various functional groups using trialkyl/triaryl phosphine and dialkyl azodicarboxylate reagents. It proceeds via an oxidation-reduction mechanism. Common applications include esterification, etherification, and N-alkylation reactions. Recent advances have focused on replacing conventional reagents to improve selectivity and yields. The Mitsunobu reaction has been widely used in the synthesis of natural products and pharmaceuticals.
This document provides an overview of conducting polymers, focusing on synthetic strategies for electron-conducting polymers. The main types of conducting polymers are introduced as electron-conducting, proton-conducting, and ion-conducting. Poly(acetylene) is discussed as the simplest conjugated polymer, with early synthesis routes producing insoluble powders and later routes enabling the production of processable films. Other discussed electron-conducting polymers include poly(diacetylene), poly(phenylene), and poly(thiophene). Precursor routes are described as an important method for obtaining processable poly(acetylene) with controlled morphology and improved properties over early synthesis methods.
The document discusses the synthetic, analytical, and therapeutic aspects of the pyrazole heterocyclic nucleus. Pyrazole rings are found in many pharmaceutical drugs due to their ease of preparation and important biological activities. Some key points:
- Pyrazoles have anti-inflammatory, antipyretic, antimicrobial, anticancer, and other therapeutic properties.
- They contain an NH group that allows for hydrogen bonding and complex formation.
- Reduction or oxidation at nitrogen atoms in the ring can yield derivative structures.
- Many established drug molecules contain the pyrazole nucleus, including celecoxib, phenylbutazone, and apixaban.
Global Strategy for Asthma Management and Prevention Updated 2009 provides guidelines for diagnosing, treating, and managing asthma. It summarizes the burden of asthma worldwide and factors influencing asthma development. Guidelines are provided for classifying asthma and assessing control. A partnership approach between doctors and patients is emphasized. Treatment involves classifying severity and controlling asthma with medications and reducing exposures. Progress is monitored regularly to maintain control.
1) The document summarizes key information about penicillin, including its discovery by Alexander Fleming in 1928, its mechanism of action inhibiting bacterial cell wall synthesis, its classification into natural, resistant, aminopenicillin, and extended-spectrum types, and its common uses treating bacterial infections like pneumonia, meningitis, and strep throat.
2) The structural activity relationship of penicillin is discussed, noting essential components like the beta-lactam and thiazolidine rings and how substitutions at different positions can impact stability and activity.
3) Potential adverse effects are outlined, ranging from diarrhea to rashes to confusion, as well as therapeutic uses for treating various bacterial infections.
This document outlines the contents of a book on functional group interconversions. It covers topics like alcohols, carboxylic acids and their derivatives, oxidation and reduction reactions, and C-C bond formation. Each chapter explains different reaction types and transformation pathways. The introduction discusses using natural products for medical treatments historically and the importance of functional group interconversions in organic synthesis.
General introduction to the course followed by a basic introduction to asymmetric or stereoselective Synthesis. Then starting the course proper by looking at substrate control.
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive functioning. Exercise causes chemical changes in the brain that may help protect against mental illness and improve symptoms for those who already suffer from conditions like depression and anxiety.
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive functioning. Exercise causes chemical changes in the brain that may help protect against mental illness and improve symptoms.
The document discusses the benefits of exercise for both physical and mental health. It notes that regular exercise can reduce the risk of diseases like heart disease and diabetes, improve mood, and reduce feelings of stress and anxiety. Staying active also helps maintain a healthy weight and keeps muscles, bones and joints healthy as we age.
This is an experiment. It is NOT a presentation. It is meant to be an interactive pdf for students to work through/revise from at their own pace. For these features to operate I guess it needs to be downloaded first.
It is based on 123.312 lectures on retrosynthesis or the design of chemical syntheses.
More problems covering asymmetric synthesis. This time with examples of substrate control, chiral reagents, and chiral catalysis. Also another example of a synthesis.
An introduction to total synthesis and retrosynthesis. A quick overview of retrosynthesis followed by one of the many syntheses of (–)-stenine. This is just an overview of the fascinating world of organic synthesis, it is not intended to teach retrosynthesis or organic synthesis. For that see some of my other lecture notes.
The document describes several reactions involving conjugate additions and discusses the stereochemical outcomes. It rationalizes the stereoselectivity using concepts like chair conformations, Felkin-Anh control, and Cram chelation control. By analyzing the transition states and preferred conformations, it is able to explain why the reactions favor one stereoisomer over another in each case.
Chiral catalysis. This is a relatively brief look at some classic examples of chiral catalysis in organic synthesis. It gives a quick overview but does not go into any detail.
1. The document describes several organic reactions and asks questions about determining product structures and rationalizing stereochemical outcomes.
2. Key concepts discussed include: conformational analysis to determine reactivity; Cram chelation control to set stereochemistry; Ireland-Claisen rearrangements maintaining configuration; and using chiral auxiliaries to induce diastereoselectivity through chelation.
3. Rationalizations of stereochemical outcomes involve analyzing transition states, identifying favored conformations, and determining approach selectivity based on steric interactions.
The document discusses the total synthesis of ibuprofen and the antihypertensive drug valsartan from starting materials.
For ibuprofen, a retrosynthetic analysis is performed to arrive at reactions to connect the starting materials in the forward sense. For valsartan, a retrosynthesis is proposed using a carboxylic acid starting material and an amine.
Lastly, a retrosynthesis is proposed for an asymmetric molecule shown, dividing it into two subunits that can be synthesized and coupled using reactions like Mitsunobu, Brown allylation/crotylation, and peptide coupling.
A look at epothilone A as it includes examples of many different forms of asymmetric synthesis. Also includes a little bit about ring-closing metathesis.
This document summarizes MacMillan's total synthesis of callipeltoside C, which employs organocatalysis and several interesting chemical transformations. The retrosynthesis splits the molecule into three fragments - the macrocyclic lactone core, carbohydrate, and a third segment prepared using organocatalysis. The forward synthesis couples these fragments in a convergent manner, with key steps including a Negishi carbometallation, organocatalytic hydroxylation, Semmelhack reaction to form the tetrahydropyran ring, and glycosidation to join the sugar moiety. The synthesis highlights the utility of retrosynthesis in simplifying complex targets and total synthesis in confirming the structure of natural products.
Gives an introduction to total synthesis and why we do it (which reminds me, I must add a picture of Everest, as I think the fact that 'it is there' is the main reason for most syntheses). Then to introduce the topic with a reasonably simple synthesis, we will look at an example of the synthesis of Tamiflu.
This document discusses organocatalysis, which uses small organic molecules rather than metals to catalyze chemical reactions. It notes the benefits of organocatalysis such as robust catalysts, new reaction types, and cleaner chemistry. Specific examples are provided of reactions catalyzed by proline, imidazolidinones, thioureas, and phosphoric acids. These catalysts form reactive intermediates like enamines and iminium ions to activate substrates for nucleophilic attack. Overall, organocatalysis is presented as a useful tool for synthetic chemists to address issues like solvent use, purification, and atom economy.
This is the biggy, the one everyone wants to achieve. Here we will be looking at metal-based chiral catalysis. We will concentrate on bisoxazoline-based Lewis acid catalysis and then look at reductions before finishing with the ubiquitous Sharpless epoxidation and dihydroxylation.
Use of stoichiometric amounts of a chiral source. The usual suspects will be discussed, including borane reagents (mostly pinene derivatives) and the Brown allylation.
Self explanatory really, this lecture looks at chiral auxiliaries. We will concentrate on oxazolidinones in alkylations, aldol reaction and the Diels-Alder reaction. There will be a couple examples of other auxiliaries.
1) The document discusses various methods of substrate control in organic reactions, focusing on how substrate conformation can influence diastereoselectivity. Allylic 1,3-strain (A1,3 strain), where substituents on the first and third carbons interact sterically, is a key concept.
2) Reactions like epoxidation and hydroboration are often highly diastereoselective when the substrate adopts a conformation that positions the smallest substituent syn to the reactive double bond to minimize A1,3 strain. The reagent then approaches from the least hindered face.
3) Directed reactions use hydrogen bonding or coordination to deliver the reagent to one
General introduction to the course followed by a basic introduction to asymmetric or stereoselective Synthesis. Then starting the course proper by looking at substrate control.
This document summarizes the synthesis of the anti-cancer compound epothilone A. It discusses the retrosynthesis of epothilone C and the synthesis of the required fragments - C1-C6, C7-C12, and C13-C21. These fragments were coupled and the ring was formed using ring-closing metathesis. Finally, epothilone C was converted to the target compound epothilone A through oxidation and reduction reactions. The synthesis utilized substrate-controlled aldol reactions, Sharpless asymmetric dihydroxylation, and ring-closing metathesis to construct the molecule with high stereoselectivity.
The document discusses various topics related to chirality and stereochemistry including:
- Different forms that can exhibit chirality beyond just tetrahedral stereocenters.
- The relationship between enantiomers, diastereomers, and meso compounds for molecules with multiple stereocenters.
- How purity of chiral compounds is measured in terms of enantiomeric excess and ratio, and diastereomeric excess and ratio.
- Common methods for determining enantiomeric excess such as derivatization reactions and chiral chromatography.
These slides are part of a talk to school teachers. They were designed to showcase some of the applications of organic chemistry, the range of natural and synthetic products. I'm not sure how much use it is without my commentary but, as always, it seems a waste to leave it on my hard drive. The second half gave a overview of chirality and stereoisomers as this topic often causes problems with students. This second half owes a lot to an excellent paper by Robert Gawley (J. Chem. Ed. 2005, 82, 1009) and just has prettier papers. This version of the talk includes a section I removed when presenting (due to time) on artificial sweeteners.
123.713A/B. Description of the Jacobsen synthesis of muconin. This is an example of total synthesis, retrosynthesis and asymmetric synthesis and shows the kind of information required in the assigment for this course.
This document summarizes reactions of alkenes including:
1. Addition of bromine to form bromonium ions and give anti-addition of bromine with stereospecificity.
2. Diol formation from epoxide ring opening, KMnO4 oxidation, and hydroboration-hydration which can give stereospecific or racemic mixtures.
3. Examples of biologically active natural products formed from alkene reactions like epothilones and dynemicin A.
The document summarizes key concepts about alkene reactions:
1) Markovnikov addition results in the addition occurring on the carbon with the most hydrogen substituents, giving the more substituted primary carbocation which is most stable.
2) Hydroboration follows anti-Markovnikov addition, with the BH3 group adding to the less substituted carbon. Oxidation then occurs with H2O2/NaOH through a 1,2-shift to give anti-Markovnikov addition.
3) Organoboranes are unstable and hydroboration involves coordination of BH3 to the alkene, allowing for stereospecific anti-Markovnikov addition
The document summarizes key concepts from Lecture Seven on alkenes and alkynes. It discusses hydrogenation of alkenes and alkynes using catalysts like Pd/C, including syn and anti addition. It provides an example of the hydrogenation of resiniferatoxin. It also explains the importance of stereochemistry in hydrogenation reactions and mechanisms of addition. Partial hydrogenation reactions using Lindlar catalyst or Na/NH3 are described. The mechanism of radical additions is shown.
This presentation includes basic of PCOS their pathology and treatment and also Ayurveda correlation of PCOS and Ayurvedic line of treatment mentioned in classics.
Executive Directors Chat Leveraging AI for Diversity, Equity, and InclusionTechSoup
Let’s explore the intersection of technology and equity in the final session of our DEI series. Discover how AI tools, like ChatGPT, can be used to support and enhance your nonprofit's DEI initiatives. Participants will gain insights into practical AI applications and get tips for leveraging technology to advance their DEI goals.
This presentation was provided by Steph Pollock of The American Psychological Association’s Journals Program, and Damita Snow, of The American Society of Civil Engineers (ASCE), for the initial session of NISO's 2024 Training Series "DEIA in the Scholarly Landscape." Session One: 'Setting Expectations: a DEIA Primer,' was held June 6, 2024.
हिंदी वर्णमाला पीपीटी, hindi alphabet PPT presentation, hindi varnamala PPT, Hindi Varnamala pdf, हिंदी स्वर, हिंदी व्यंजन, sikhiye hindi varnmala, dr. mulla adam ali, hindi language and literature, hindi alphabet with drawing, hindi alphabet pdf, hindi varnamala for childrens, hindi language, hindi varnamala practice for kids, https://www.drmullaadamali.com
Exploiting Artificial Intelligence for Empowering Researchers and Faculty, In...Dr. Vinod Kumar Kanvaria
Exploiting Artificial Intelligence for Empowering Researchers and Faculty,
International FDP on Fundamentals of Research in Social Sciences
at Integral University, Lucknow, 06.06.2024
By Dr. Vinod Kumar Kanvaria
Strategies for Effective Upskilling is a presentation by Chinwendu Peace in a Your Skill Boost Masterclass organisation by the Excellence Foundation for South Sudan on 08th and 09th June 2024 from 1 PM to 3 PM on each day.
Main Java[All of the Base Concepts}.docxadhitya5119
This is part 1 of my Java Learning Journey. This Contains Custom methods, classes, constructors, packages, multithreading , try- catch block, finally block and more.
7. Reductive work-up: oxidative work-up: oxidative work-up:
H2O2
O H+ O
O O OH O
O H O O O H O H
O O O H
O O
OH
O OH H O H O
O O mechanism isn’t so O
O S clear...I’m ok up to the H H
O S aldehyde then made it up ...
O H H H
O O O OH
H O H O
O H
O O repeat O H
O
O O CO2H CO2H
OH
the ozonide is then OH OH oxidation could occur via a
broken down on hydride shift or it could
work-up be radical
55 56 57
Care must be taken in the Chromium-based oxidation
oxidation of alcohols... reagents: Jones reagent
always goes to
carboxylic acid
H H [O] H [O] OH CrO3,
H H H2SO4 OH
R OH R O R O
oxidation of R OH R O
R H [O] R
alcohols often hard to stop
oxidation at aldehyde CrO3,
R OH R O
stage R H H2SO4 R
R R
X
[O] R OH R O
probably should
have a bottle of can oxidise tertiary alcohols
vinegar here... R OH but it requires C-C bonds
to be broken harsh, acidic conditions limit its use
58 59 60
Chromium-based oxidation Cl
Chromium-based O O
reagents: Pyridinium oxidation reagents:
Cr O Cr O Cr O
chlorochromate O O N Pyridinium N
O H Dichromate O O H 2
H H PCC H H H
PDC PDC
R OH NO H2O R O DCM R OH DMF
H OH
R H PCC R
R O R O
R OH R O
many chromium reagents are
less acidic (but still acidic!) carcinogens mild & interesting selectivity
61 62 63