Synthesis of (-)-Chamobtusin A from (+)-Dehydroabietylamine.

Chamobtusin A, a unique diterpene alkaloid isolated from Chamaecyparis obtusa cv. tetragon, is considered to be biosynthesized from an abietane diterpenoid. On the basis of this biosynthetic hypothesis, ferruginol (15) was synthesized from (+)-dehydroabietylamine and then biomimetically transformed into (-)-chamobtusin A in 6 steps (12 steps from (+)-dehydroabietylamine).

Synthesis of (±)-chamobtusin A by a presumed biomimetic aza-cyclization.

A total synthesis of (±)-chamobtusin A has been accomplished on the basis of our presumed biosynthetic pathway: the imine formation of keto aldehyde followed by intramolecular aza-Michael addition.