Search

N-acylation reaction offers an opportunity to develop an efficient synthesis of amide group-containing molecules. We found that N-acyl carbazoles showed remarkable selectivity in transamidation. St...

Facile and stereoselective syntheses of three different kinds of deuterium-labelled geranylgeraniol analogs have been achieved. LiAlD4 is used as the deuterium source to ensure high deuterium incor...

Stereoselective synthesis of both optically active cis- and fra/M-1-amino-2-hydroxycyclohexane-l-carboxylic acids (Ahhs) la and 1b was accomplished by an asymmetric version of the Strecker synthesis. Stereochemical aspects of their chiral induction processes are investigated.

A series of optically active α,α-disubstituted α-amino acids have been synthesized starting with an achiral or a racemic α-hydroxy or α-diazo ketone. In the present synthesis, the key transformation is an asymmetric version of the Strecker synthesis. An α-acyloxy ketone having a chiral amino acid as the acyloxy group afforded cyclic α-amino nitrile in a highly stereoselective manner; in this reaction the amino group and the chirality were diastereoselectively transplanted into the internal ketone group via an imine-enamine equilibrium of the cyclic ketimine intermediate. Oxidation of the amino group followed by removal of the resulting imino group and hydrolysis of the nitrile group afforded α-hydroxymethyl α-amino acid. The use of L-amino acid as the acyloxy group gave R enantiomer, and its S enantiomer was obtained when D-amino acid was employed. Some problematic processes that remained in the Strecker synthesis, i.e., preparation of the starting α-acyloxy ketone and oxidative conversion of α-amino nitr...