Studies on the Alkaloids of Menispermaceous Plants. CLXXXIX

Synthesis of Tetrandrine

Abstract

Tetrandrine (V) was synthesized by the Ullmann condensation of L-N-methylcoclaurine (II), obtained by cleavage of isotetrandrine (I) with sodium in liquid ammonia, and L-3′, 8-dibromo-N, O, O-trimethylcoclaurine (IV), obtained by bromination of (II) followed by methylation. (V) was obtained as its crystalline picrate and identified with natural L, L-tetrandrine picrate. In this reaction, O, O-dimethyl-bebeerine (VI) should have been formed at the same time and this is now under investigation.