STEREOSPECIFIC SYNTHESIS OF DEOXYHARRINGTONINE AND HOMOHARRINGTONINE

The asymmetric synthesis of deoxyharringtonine and homoharringtonine has been described.The stereospecific condensation of chiral a-sulfinylester (Ⅰ) and corresponding a-keto-acyl-cephalotaxine (Ⅱa) and (Ⅱb) was used to introduce the asymmetric C₂' with the desired configuration. The condensation products (Ⅲa) and (Ⅲc) wero desulfurized with aluminum amalgam to give compounds (Ⅳa) and (Ⅳc) which were hydrolyzed with trifluoroacetic acid to remove t-butyl group. The final products were obtained by methylation with diazomethane.The higher steric selectivity in the reaction of chiral (+)Ra-sulfinylester (Ⅰ) was again demonstrated.