Enantioselective catalysis using planar chiral eta(6)-arene chromium complexes: 1,2-diols as cycloaddition catalysts

A highly selective Diels-Alder catalyst has been prepared from a commercial ly available tetra-hydronaphthalene diol. Stereocontrol is greatly enhanced by introduction of a planar chiral arene chromium tricarbonyl group, achie ved by face selective complexation. The factors influencing stereoselectivi ty with the catalyst have been investigated and delineated. Under optimal c onditions, the catalyst gives >95% e.e. and 98:2 exo:endo ratio in the cycl oaddition of methacrolein and cyclopentadiene. (C) 2000 Elsevier Science Lt d. All rights reserved.