Unique regio- and stereoselectivity in the allylation of benzaldehyde with 2-substituted allylzincs generated by umpolung of π-allylpalladium
作者:Masamichi Shimizu、Masanari Kimura、Shuji Tanaka、Yoshinao Tamaru
DOI:10.1016/s0040-4039(97)10657-8
日期:1998.2
alpha,beta-Disubstituted allylzincs with alkoxycarbonyl as the beta-substituent, generated via an umpolung of in situ generated pi-allylpalladium by transmetallation with diethylzinc, react with benzaldehyde at the most substituted allylic terminus to provide syn-gamma-butyrolactones 4 exclusively, while those with electron-donating Me, i-Pr, or OMOM as the beta-substituents react at both allylic termini to give mixtures of syn-2, anti-2 and Z-3. alpha,beta,gamma-Trisubstituted allylzincs provide Z,anti-adducts 5 exclusively. (C) 1998 Elsevier Science Ltd. All rights reserved.