ASYMMETRIC SYNTHESES OF SALVIA-MILTIORRHIZA ABIETANOID ORTHO-QUINONES - METHYL TANSHINONATE, TANSHINONE-IIB, TANSHINDIOL-B, AND 3-HYDROXYTANSHINONE

The Diels-Alder reaction of 3-methyl-4,5-benzofurandione with vinylcyclohexene derivatives using either high-pressure or ultrasound promotion has led to the asymmetric synthesis of methyl tanshinonate, tanshinone IIB, tanshindiol B, and 3-hydroxytanshinone. The abietanoid diterpenes are active constituents of the Chinese traditional medicine, Dan Shen, prepared from the roots of Salvia miltiorrhiza Bunge. As a result, the absolute stereochemistry of these natural products has been assigned: (-)-(4S)-methyl tanshinonate, (-)-(4S)-tanshinone IIB, (-)-(3S,4R)-tanshindiol B, and (+)-(3S)-3-hydroxytanshinone. © 1990, American Chemical Society. All rights reserved.