PROCESS FOR THE PREPARATION OF OPTICALLY ACTIVE (4E)-5- HALO-2-ALKYLPENT-4-ENOIC ACIDS AND THEIR ESTER DERIVATIVES

摘要

A process for the preparation of optically active (4E)-5-halo-2-alkylpent-4-enoic acids and their ester derivatives by a stereoselective synthesis which employs camphorsultam as chiral auxiliary is disclosed; in particular methyl (2S, 4E)-5-chloro-2-isopropylpent-4-enoate is prepared, which is a key intermediate in the manufacturing of the new anti-hypertension drug Aliskiren. Furthermore novel N- (5-halo-2-alkylpent-4- enoyl) camphorsultams are provided. A process for the hydrolysis of substituted N-acylcamphorsultams with strong acids is also provided.