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.
Este documento apresenta os conceitos fundamentais de projeto de segurança contra incêndio em edifícios (SCIE) e interpretação de peças desenhadas, incluindo a estrutura e conteúdo do projeto de especialidade de SCIE, a simbologia gráfica a utilizar e a legislação aplicável.
Este documento apresenta os conceitos fundamentais de projeto de segurança contra incêndio em edifícios (SCIE) e interpretação de peças desenhadas, incluindo a estrutura e conteúdo do projeto de especialidade de SCIE, a simbologia gráfica a utilizar e a legislação aplicável.
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.
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.
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 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).
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.
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.
Use of stoichiometric amounts of a chiral source. The usual suspects will be discussed, including borane reagents (mostly pinene derivatives) and the Brown allylation.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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 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).
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.
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.
Use of stoichiometric amounts of a chiral source. The usual suspects will be discussed, including borane reagents (mostly pinene derivatives) and the Brown allylation.
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.
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.
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.
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.
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.
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.
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.
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.
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 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.
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.
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 describes improvements made to the process for manufacturing the potential therapeutic compound ELN 296571. It summarizes the original multi-step synthesis route and key intermediate compound ELN 361973. The route was optimized to require fewer steps and produce ELN 361973 in higher yields and purity. Later, production of the important intermediate ELN 361973 was outsourced to improve the overall process.
This chapter outline discusses DNA and RNA structure and function, including:
- The discovery that DNA is the genetic material through experiments with viruses.
- The double helix structure of DNA determined by Watson and Crick based on data from Franklin and others.
- DNA replication through semiconservative replication to produce identical copies.
- Transcription of DNA to mRNA and the three types of RNA (mRNA, tRNA, rRNA).
- Translation of mRNA using tRNA to specify amino acid sequence and produce proteins according to the genetic code.
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.
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.
More problems covering asymmetric synthesis. This time with examples of substrate control, chiral reagents, and chiral catalysis. Also another example of a synthesis.
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 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.
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.
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.
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.
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.
Assessment and Planning in Educational technology.pptxKavitha Krishnan
In an education system, it is understood that assessment is only for the students, but on the other hand, the Assessment of teachers is also an important aspect of the education system that ensures teachers are providing high-quality instruction to students. The assessment process can be used to provide feedback and support for professional development, to inform decisions about teacher retention or promotion, or to evaluate teacher effectiveness for accountability purposes.
How to Build a Module in Odoo 17 Using the Scaffold MethodCeline George
Odoo provides an option for creating a module by using a single line command. By using this command the user can make a whole structure of a module. It is very easy for a beginner to make a module. There is no need to make each file manually. This slide will show how to create a module using the scaffold method.
A Strategic Approach: GenAI in EducationPeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
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.
Thinking of getting a dog? Be aware that breeds like Pit Bulls, Rottweilers, and German Shepherds can be loyal and dangerous. Proper training and socialization are crucial to preventing aggressive behaviors. Ensure safety by understanding their needs and always supervising interactions. Stay safe, and enjoy your furry friends!
বাংলাদেশের অর্থনৈতিক সমীক্ষা ২০২৪ [Bangladesh Economic Review 2024 Bangla.pdf] কম্পিউটার , ট্যাব ও স্মার্ট ফোন ভার্সন সহ সম্পূর্ণ বাংলা ই-বুক বা pdf বই " সুচিপত্র ...বুকমার্ক মেনু 🔖 ও হাইপার লিংক মেনু 📝👆 যুক্ত ..
আমাদের সবার জন্য খুব খুব গুরুত্বপূর্ণ একটি বই ..বিসিএস, ব্যাংক, ইউনিভার্সিটি ভর্তি ও যে কোন প্রতিযোগিতা মূলক পরীক্ষার জন্য এর খুব ইম্পরট্যান্ট একটি বিষয় ...তাছাড়া বাংলাদেশের সাম্প্রতিক যে কোন ডাটা বা তথ্য এই বইতে পাবেন ...
তাই একজন নাগরিক হিসাবে এই তথ্য গুলো আপনার জানা প্রয়োজন ...।
বিসিএস ও ব্যাংক এর লিখিত পরীক্ষা ...+এছাড়া মাধ্যমিক ও উচ্চমাধ্যমিকের স্টুডেন্টদের জন্য অনেক কাজে আসবে ...
This presentation includes basic of PCOS their pathology and treatment and also Ayurveda correlation of PCOS and Ayurvedic line of treatment mentioned in classics.
A workshop hosted by the South African Journal of Science aimed at postgraduate students and early career researchers with little or no experience in writing and publishing journal articles.
How to Fix the Import Error in the Odoo 17Celine George
An import error occurs when a program fails to import a module or library, disrupting its execution. In languages like Python, this issue arises when the specified module cannot be found or accessed, hindering the program's functionality. Resolving import errors is crucial for maintaining smooth software operation and uninterrupted development processes.
1. FUNCTIONALGROUP
123.312
INTERCONVERSIONS functional group
CHAPTER7
interconversions H H O H H
Cr O H H
R O S
OH
CHAPTER seven R O
reduction
previously we had looked at
oxidations now we turn our attention to
E
the opposite, reduction
1 2 3
need to be able to control OH
oxidation
now adding hydrogen or Text H
chemoselectivity N
removing oxygen (or other HO
R H Clheteroatom) R R N O C O
HO salmefamol OMe
O O O
R OH
R R1/H R OH H2N NH2 O O O
Cl Cl O Cl Cl vs vs
R NH2 R2
R R R OR1 Cl Cl R1 H R1 R2 R1 O
R1O OR1 O
R Cl
R R R NH2
lets approach this by example
& look at the synthesis of this
Reduction anti-asthma drug
4 5 6
starting material contains many hydrogenolysis & reductive hydrogenolysis & reductive
reducible groups amination amination
OMe OMe
O OH O OH
O O O OH H2, Pd / C, O OH H2, Pd / C, O OH
MeO H+, ketone MeO H+, ketone
MeO NaBH4 MeO N MeO N MeO
HO HO
HN HN
N N Ph Ph HO Ph Ph HO
HO HO
Ph Ph Ph Ph
O O
hydrogenation reductively OMe OMe it also reduces imine formed
sodium borohydride only by condensation of amine &
reacts with the ketone & cleaves benzyl groups (as seen
earlier) but... ketone in a process called
not the ester reductive amination
7 8 9
3. Reduction of esters
NaBH4 R1
O
O
R2
LiAlH4
R1
H H
OH
H
O
R2
LiAlH4
O O O O O O O O
R1 H R1 R2 R1 Cl R1 OR2 R1 NR2
R1 H R1 R2 R1 Cl lithium aluminium hydride
reduces esters all the way
only reduces reactive c=o bonds down to alcohols reduces nearly all carbonyls
19 20 21
mechanism of lithium mechanism of lithium by-product is also a (less)
aluminium hydride reduction aluminium hydride reduction powerful reductant...
H Li Li H Li Li
O O O O
H Al H R2 R1 R2 H Al H R2 R1 R2
H R1 O O H R1 O O
H H
H H
H
O
R2
H H
H
O
R2 AlH3
Li
Al
H Li Li
Al
H Li
O
O H O O H O
R1 H Al H R1 H Al H
H
H H R1 H H
H H R1 H R1 H
H
AlH3 H AlH3 H
O H O O H O cation important;
again, note H– is remove it &
R1 not the reductant R1 ...could be termed a
R1 H R1 H reaction stops
H
H H H
H H more selective reagent!
22 23 24
Reduction of amides mechanism of lithium aluminium amine normally a poor leaving group
hydride reduction of amides
Li
H O Li
O
H Al H R2
R1 N NR22
H R1
H
O H H R2 Li
AlH3
O O
R1 N
R2
LiAlH4
R1 N
R2
H Al H
H
NR22 O
AlH3
R1 NR22
X R1 H R
2
N
R2
R1 NR22 H
R2 R2 H H R1
H
second reduction (of the
lithium aluminium
H H iminium cation) does not Amine anions often used as bases
hydride can perform R2 require metal cation as it (think LDA) they have high pka so
R1 N are poor leaving groups
this reduction is already charged
R2
25 26 27