An Efficient Synthesis of Optically Active (2R,3R)‐2‐Methyl‐3‐[(1R)‐1‐methylprop‐2‐enyl]cyclopentanone, a Useful Chiral Building Block for Synthesis of Vitamin D and Steroids.

Abstract

Abstract An efficient synthesis of optically active (2R,3R)-2-methyl-3-[(1R)-1-methylprop-2-enyl]cyclopentanone, a useful chiral building block for synthesis of vitamin D and steroids, has been developed starting from readily accessible optically active secondary propargyl phosphate (R)-2 , where the asymmetric Michael addition of a chiral allenyltitanium to alkylidenemalonate 3 is a key reaction.