Milan Soukup

Enzymatic preparation of homochiral 2-isobutyl succinic acid derivatives

Abstract An efficient enzymatic procedure for the enantio- and regioselective monohydrolysis of diethyl 2-isobutyl succinate [bd3] using subtilisin Carlsberg has been developed. The product (R)-2-isobutyl succinic acid 4-ethyl ester 4 , a collagenase inhibitor building block, was obtained in high enantiomeric excess (>99%) and yield (>45%). Similarly, (R)-2-isobutyl succinic acid 4-nitrile 2 was produced in 98% ee from its ethyl ester 1 .

Strategies for Building the Carbon Skeleton

Modern synthetic organic chemistry would permit the preparation of carotenoids by an almost countless number of strategies. In reality, however, the few methods and strategies that became established early in this century have since been used repeatedly and some of these have been developed to the scale of industrial syntheses. The aim of this Chapter is to provide a guide to the simplest route to a particular target carotenoid.

Preparation of (7Z) - and (7Z,11Z) - vitamin A

An efficient access to (7Z)- and (7Z,11Z)-vitamin A is described. Following the addition of a C6-acetylenic building block to 2,6,6-trimethylcyclohexanone (2), dehydration of the tert. alcohol 3 and formation of the C15-Wittig salt, the (7Z)-geometry was introduced by partial hydrogenation of the triple bond over Raney-nickel. Following Wittig reaction with (E)-2-methyl-4-acetoxy-2-butenal gave a mixture of the title compounds 8 and 9 which could easily be separated.