Efficient synthesis of (-)-clausenamide

Abstract

A new method for the synthesis of (-)-clausenamide was reported. (-)-Clausenamide was synthesized starting from the inexpensive trans-cinnamic acid. The synthesis was carried out over five steps, and the overall yields were 8.9% (99.9% ee). Compared with the multi-step asymmetric synthesis methods reported in the literature, the raw materials used in this method are inexpensive. The overall method is easy to carry out. Furthermore, the reaction takes place under very mild reaction conditions (25 °C). Anhydrous and very low temperature (-78 °C) conditions can be avoided. The column chromatography technique need not be conducted after each reaction step. Hence, this is a suitable method to carry out the large-scale synthesis of (-)-clausenamide. The structures were confirmed using the 1 H NMR, 13 C NMR, and MS techniques.