Intramolecular transacetylation in salvinorins D and E.

Extraction of fresh Salvia divinorum leaves afforded salvinorins E and D as potential biosynthesis precursors of salvinorin A, a major metabolite and a potent hallucinogen. Attempts at HPLC purification of salvinorin E (2) with acetonitrile as a solvent revealed an equilibrium with its regioisomer, salvinorin D (3), in a 3:5 ratio. The presence of both compounds was readily observed in the (1)H NMR spectrum. This spontaneous formation of the mixture of isomers occurs via a dynamic intramolecular transacetylation process.

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.

(2S,4aR,6aR,7R,9S,10aS,10bR)-7-Carb-oxy-2-(3-fur-yl)-6a,10b-dimethyl-4,10-dioxoperhydro-benzo[f]isochromen-9-yl acetate.

The asymmetric unit of the title compound, C(22)H(26)O(8), contains two crystallographically independent mol-ecules with closely comparable conformations (r.m.s. overlay = 0.54 Šfor 30 non-H atoms). All six-membered rings display chair conformations, with a slight distortion for the lactone ring. The mol-ecules are connected by O-H⋯O hydrogen bonds into chains along [010], with the independent mol-ecules segregated into separate chains. The two mol-ecules in the asymmetric unit face each other in a head-to-tail fashion, with the furan ring of one mol-ecule turned towards the carboxylic acid terminal of the other mol-ecule.