Abstract: Isoharringtonine (1), one of the four cephalotaxine esters exhibiting antitumor activity was synthesized by first treating the cephalotaxine ester of keto acid with α-benzyloxy-α-bromoacetic acid ester instead of the classical α-bromoacetic acid in the Reformatsky reaction to give a mixture of four stereoisomers. The mixture could only be separated into two parts A and B by chromatotron. A and B were hydrogenated separately with Pd/C. The reaction products obtained were separated on chromatotron to give A_H1, A_H2 and B_H1, B_H2 correspondingly. The m p, α and various spectra of B_H1 are indentical with those of the natural isoharringtonine. The configurations of the rest three isomers were postulated based upon their NMR spectra in combination with comformational analysis.