Synthesis of Optically Active Monoacid Side‐Chains of Cephalotaxus Alkaloids

This is the authors' abstract. We don't add key points for this paper.

The general preparation of enantiopure monoacid side‐chains of several esters of cephalotaxine is described. The strategy, similar to Weinreb's approach to the synthesis of deoxyharringtonine, used as key intermediate the chiral nonracemic epoxide 11a prepared from the commercially available monomethyl itaconate (8). The key step of the strategy was the ring‐opening of the epoxide 11a by using different organocuprate nucleophiles. Hydrogenolysis as the final step gave the monacid side‐chains of the corresponding esters of cephalotaxine in moderate to good overall yields from epoxide 11a.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)