作者:Mar Gómez-Gallego、Marı́a J Mancheño、Pedro Ramı́rez、Carmen Piñar、Miguel A Sierra
DOI:10.1016/s0040-4020(00)00204-0
日期:2000.7
Chromium and tungsten styryl Fischer carbene complexes 12 and 15 were transformed into Z-vinyl ether 13 and E-allyl ether 14 by NaBH4 reduction in EtOH. Deuterium labeling experiments demonstrate that the reaction occurs by the initial addition of the hydride to the carbene carbon atom, followed by a 1,3-rearrangement of the M(CO)(5) fragment. The process could involve the participation of an eta(3)-allyl chromium intermediate. The reaction is general and has been applied to a series of alpha,beta-unsaturated alkoxy and aminocarbene complexes. In the case of chromium and tungsten alkynyl carbenes 38 and 39, NaBH4 reduction exclusively yields E-allyl ether 14. The intermediacy of an allenyl complex 41 obtained after the 1,3-rearrangement of the metal center is confirmed by deuterium labeling experiments. (C) 2000 Elsevier Science Ltd. All rights reserved.