Salvinorins J from Salvia divinorum: mutarotation in the neoclerodane system.

A search for biosynthetic precursors of salvinorin A (1) led to the isolation of a new neoclerodane diterpenoid hemiacetal mixture, salvinorins J (2), from the chloroform extract of Salvia divinorum. A leaf surface extraction method was used on S. divinorum, affording a chlorophyll-free extract containing predominantly neoclerodane diterpenoids, including the new salvinorins J (2) and 14 known analogues. Salvinorins J (2) represent an example of a neoclerodane hemiacetal (lactol) susceptible to mutarotation with the formation of an equilibrium mixture of C-17 epimers.