Ketimine 3-keto ester

Only limited success has been reported in the reduction of ketimines due to the low electrophilicity of the imine carbon and the rapid equilibration between the (E)- and (Z)-isomers. However, high enantioselectivity was achieved in catalytic reduction of imines of keto esters (Equation (261))1125 and oximes of acetophenone (Equation (262))1089,1125-1131 cyclic ketones (Equation (263)),1127 and a ketone possessing a boryl group (Equation (264)).1128... 

Ketene, 104, 232 Ketimines, 414 -Ketoacetals, 221 0-Keto allenes, 230, 231 a-Ketocarboxylic acids, 184 1 -Keto-7,7-dimethylnorcarane, 181 a-Keto esters, 237, 245 Ketones, 229, 274 Ketones, resolution, 58, 59... 

The P-chirogenic organocatalysts 294 and 295 were found to promote the enantioselective aza-Morita-Bayhs-Hillman reaction of ketimines derived from acyclic a-keto esters. In the P-chirogenic organocatalyzed aza-Morita-Baylis-Hillman reactions, a,a-disubstituted a-amino acid derivatives 296 were obtained in high yields and with high enantioselectivities (up to 97% cc) (Scheme 98) [195]. 

The modification of the Peterson reaction using an N-trimethylsilylamide anion instead of an a-silyl carbanion offers a promising route to the corresponding imines. Treatment of N-(p-tolyl)-N-trimethylsilylamide anion with carbonyl compounds yields the corresponding ketimines [400]. In particular, LiHMDS has been utilized for the preparation of N-trimethylsilylimines, which are useful as masked imine derivatives in the synthesis of yS-lactam antibiotics [401-407]. Reactions of LiHMDS with non-enolizable aldehydes, enolizable aldehydes, ketones, a diketone, and a-keto esters give the respective imines (Scheme 2.153) [408-413]. Chloro-trimethylsilane is added to convert the generated lithium trimethylsilanolate into hexamethyldisiloxane. 

The in situ formation of a ketimine provided the cyclization precursor, which furnished on imine arylation the densely functionalized dibenzodiazepine derivative (Scheme 13.96). When the keto functionality was replaced by an ester moiety, which is reactive toward ammonia under the reaction conditions, an amide cyclization precursor is generated in situ (Scheme 13.97). The arylation of the spawned amide by the aryl chloride fragment furnished the dibenzoxazepinone derivatives in good to excellent yields. 

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