Selective Reduction of 7-Demethylsinomenine

Several borohydride reagents: sodium borohydride, sodium cyanoborohydride, soudium acetoxyborohydride and soudium triacetoxyborohydride were screened, respectively, for the reduction of 7-demethylsinomenine, which was an α,β-dicarbonyl compound derived from sinomenine. Highly regio- and stereo-selectivity was acquired when sodium cyanoborohydride or NaBH(OAc)3 was used. The product was structurally confirmed as 7R configuration by NMR, X-ray crystal diffraction analysis. Some preliminary discussion was also made on the mechanism of the selective reduction.