Nickel-catalyzed cross coupling of cyclopropyl Grignard reagents with benzylic dithioacetals. Regioselective ring opening of cyclopropylcarbinyl organometallic intermediates. Novel synthesis of substituted dienes
Journal
Organometallics
Journal Volume
13
Journal Issue
4
Pages
1487-1497
Date Issued
1994
Author(s)
Abstract
The reactions of various cyclopropylmagnesium bromides with benzylic dithioacetals afforded the corresponding substituted conjugate dienes in good yields. These reactions can be considered as using cyclopropyl anion as an allyl anion synthon. The reaction shows high regio- and stereoselectivity to give E isomers predominantly, if not exclusively. The nature of the substituent(s) in the ring-opening process in the (cyclopropylcarbinyl)nickel intermediate has been investigated in detail. An aryl or vinyl substituent gives regioselective ring opening at the more substituted carbon‒carbon bond, an alkyl substituent being unselective. β-Heteroatom elimination in these nickel-catalyzed cross-coupling reactions has been used for regioselective synthesis of 1,4-dienes. © 1994, American Chemical Society. All rights reserved.
Type
journal article