A diastereo- and enantioselective propargylic substitution reaction between propargylic carbonates and α-substituted nitroacetates catalyzed by a Cu-pybox complex is described. This method allows the preparation of a series of non-proteinogenic quaternary α-aminoacid precursors featuring two contiguous stereogenic centers and a terminal alkyne moiety in high yields with good to excellent diastereo-
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.
Efficient Palladium-Catalyzed Cross-Coupling of Highly Acidic Substrates, Nitroacetates
作者:Alison E. Metz、Simon Berritt、Spencer D. Dreher、Marisa C. Kozlowski
DOI:10.1021/ol203303b
日期:2012.2.3
Palladium-catalyzed cross-coupling conditions were developed that efficiently afford 2-aryl-2-nitroacetates from aryl bromides and the very acidic nitroacetates.