The Mechanism of Enamine Formation The overall equation for enamine formation from cyclohexanone (a ketone) and pyrrolidine (a 2º-amine) is shown here. Writing a mechanism for this reaction provides a good test of ones' understanding of acid-catalyzed processes.

2009年10月31日 · Asymmetric Enamine Catalysis O + NO2 O H N H CO2H 30mol% DMSO NO 2 O OH 68%, 75% ee List, B.; Lerner, R. A.; Barbas III, C. F. J. Am. Chem. Soc. 2000, 122, 2395-2396. The First Conceptualization of Asymmetric Enamine Catalysis: Asymmetric Michael Reactions Asymmetric Aldol Reactions Asymmetric Mannich Reactions This concept has been ...

The five-membered cyclic 2º-amine pyrrolidine is widely used for enamine reactions, in part because this steric hindrance is minimized. Examples of Enamine Reactions As noted, N-alkylation of enamines is common for aldehydes and some ketones.

23.12 The Stork Enamine Reaction Michael rxn with an enamine nucleophile instead of an enolate: Enamines behave similarly to enolates in that they have a partial negative charge on their alpha-C. 3 N N nucleophilic !-C N O 1. 2. HO+ O O O N O protonates the enolate and hydrolyzes the iminium H3O+ N O H N

D. Enamine Formation. The previous reactions have all involved reagents of the type: Y–NH 2, i.e. reactions with a 1º-amino group. Most aldehydes and ketones also react with 2º-amines to give products known as enamines. Two examples of these …

D) I gives an enamine & II gives an imine 19 Which reaction or sequence of reactions would be best used to convert cyclohexanone to cis -1,2-cyclohexanediol? A) PCC in CH 2 Cl 2 and base

The most basic site in the reactants is the pyrrolidine nitrogen atom. Its conjugate acid is shown on the left above.

The imine or enamine intermediates are normally not isolated, but are immediately reduced to the amine product. To see an animated mechanism for imine formation . Another general method for preparing all classes of amines makes use of amide intermediates, easily made from ammonia or amines by reaction with carboxylic acid chlorides or anhydrides.

2007年5月18日 · Antibody catalyzed aldol rxn with broad reaction scope Barbas et al, Science 1997, 278, 2085

Enamine Formation Acetal Formation; CH 3 CH 2 OH H + catalyst, –H 2 O: H 2 O ( pH = 4 ) CH 3 NH 2 H + catalyst, –H 2 O: KMnO 4 in aqueous base: CH 3 CH 2 MgBr (workup with H 3 O +) NaC≡CCH 2 CH 2 CH 3 (workup with H 3 O +) LiAlH 4 (workup with H 3 O +) NaBH 4 in aqueous alcohol: HCN ( pH = 7.5 ) (CH 3) 2 NH H + catalyst, –H 2 O: Jones ...