Regioselective thionocarbonation of ginkgolides: facile preparation of ginkgolide J

Ginkgolide J, a minor constituent of terpene trilactone mixture of Ginkgo biloba leaves extract, can be readily prepared from an abundant ginkgolide C in two steps: thionocarbonation and subsequent deoxygenation. Regioselectivity of the first thionocarbonation step can be controlled by a proper choice of the base and solvent combination.