Zirconium-catalyzed asymmetric carboalumination (ZACA reaction) of 1,4-dienes

Variously substituted 1,4-dienes containing a terminal vinyl (H2C=CH) group, readily undergo the ZACA reaction with Me3Al and higher alkylalanes in a 1: 1 molar ratio in the presence of a catalytic amount (1-5 mol %) of bis[(1-neomenthyl)indenyl]zirconium dichloride in good yields and in good enantioselectivity (70-92% ee), thereby providing an efficient and convenient route to various alkene-containing chiral natural products. Only the reaction of the parent 1,4-pentadiene is accompanied by extensive racemization. (c) 2006 Elsevier Ltd. All rights reserved.