Catalytic Enantioselective Halolactonization of Enynes and Alkenes
作者:Wei Zhang、Na Liu、Casi M. Schienebeck、Kyle Decloux、Suqing Zheng、Jenny B. Werness、Weiping Tang
DOI:10.1002/chem.201103809
日期:2012.6.4
developed for the enantioselectivehalolactonization of (Z)‐1,3‐enynes and 1,1‐disubstituted alkenes. In the case of 1,3‐enynes, the carboxylate nucleophile and halogen electrophile were added to the conjugated π‐system from the same face. Up to 99 % ee was achieved for the 1,4‐syn‐bromolactonization of conjugated (Z)‐1,3‐enynes. Based on the results from the enynehalolactonization, a second generation
On the Chlorenium Source in the Asymmetric Chlorolactonization Reaction
作者:Roozbeh Yousefi、Daniel C. Whitehead、Janet M. Mueller、Richard J. Staples、Babak Borhan
DOI:10.1021/ol102850m
日期:2011.2.18
N-Acylated N-chlorohydantoins are shown to be competent chlorenium sources in the (DHQD)(2)PHAL-mediated asymmetric chlorolactonization. The derivatives demonstrate the exact role of the N1 and N3 chlorine atoms in the parent dichlorohydantoins with the N1 chlorine serving as an inductive activator and the N3 chlorine being delivered to the substrate. The putative associated catalyst/chlorine source complex was experimentally demonstrated through a series of matched/mismatched experiments employing chiral N-chlorinated hydantoins.