Optically active naphthohydroquinone and naphthoquinone tricarbonyl chromium complexes via diastereoselective benzannulation with sec alcohol auxiliaries

The asymmetric benzannulation of optically active aryl or vinyl (alkoxy)carbene chromium complexes bearing chiral sec. alcohol auxiliaries with 3,3-dimethyl-1-butyne proceeds with moderate to high diastereoselectivities. The best results are obtained with (-)- and (+)-menthol derivatives. The stereoselectivity depends on the unsaturated carbene substituent and the solvent used. Enantiopure S-5-10-eta(6)-tricarbonyl-(2-tert.-butyl-1,4-naphthoquinone)chromium 25 was synthesized by intramolecular haptotropic migration of the tricarbonyl chromium fragment within the benzannulation product followed by deprotection and oxidation. (C) 1997 Elsevier Science Ltd.