STUDY ON ASYMMETRICAL SYNTHESIS OF STEROIDS.Ⅶ.A NOVEL METHOD FOR SYNTHESIS OF 2-ALKYL-2-(3'-OXO-6'-METHOXYCARBONYL-) HEXYL-1,3-CYCLOPENTANDIONE

The 2-alkyl-2-(3′-oxo-6′-methoxycarbonyl-) hexyl-1, 3-cyclopentanedione(2) which can be converted to the optically active synthons by microbial asymmetric reduction or asymmetrical induction of S-amino acids is a key intermediate for total synthesis of steroids. Compound 2 was synthesized from acrolein (4) through the reaction sequence shown in scheme. The overall yields from 4 to 2 were 13% (R=CH₃) and 17% (R=C₂H₅) respectively.