Palladium-Catalyzed Alkylation of 1,4-Dienes by CH Activation
作者:Barry M. Trost、Max M. Hansmann、David A. Thaisrivongs
DOI:10.1002/anie.201200601
日期:2012.5.14
Activated: the title reaction proceeds with a broad range of nucleophiles and variously substituted 1,4-dienes under mild conditions, and provides direct access to the corresponding 1,3-diene-containing products with high regio- and stereocontrol (see scheme; 2,6-DMBQ=2,6-dimethylbenzoquinone, EWG=electron-withdrawing group). This is the first catalytic allylic C-H alkylation that proceeds in the absence of sulfoxide ligands.
Pentadienylzirconium compounds: easily accessible new reagents for selective pentadienylation reactions
2,4-Pentadienylzirconium complexes are generated from 2,4- or 2,2'-pentadienyl ethers in turn. These compounds react in situ with aldehydes and ketones in a totally gamma -regioselective manner and with predominant anti stereoselectivity to produce bis(homoallylic) alcohols in good yields. Iodocyclization of one of these alcohols represents regio- and stereocontrolled short entry to functionalized tetrahydrofurans. (C) 2001 Elsevier Science Ltd. All rights reserved.