1392140-50-9Relevant academic research and scientific papers
Dissecting the stereocontrol elements of a catalytic asymmetric chlorolactonization: Syn addition obviates bridging chloronium
Yousefi, Roozbeh,Ashtekar, Kumar Dilip,Whitehead, Daniel C.,Jackson, James E.,Borhan, Babak
, p. 14524 - 14527 (2013/10/22)
We report absolute and relative stereochemistry of addition in enantioselective chlorolactonizations of 4-phenyl-4-pentenoic acid and its related t-butyl ester, catalyzed by (DHQD)2PHAL. Predominant syn addition of the chlorenium and the nucleophile across the olefin is observed. As shown by isotopic labeling, NMR spectroscopy, and derivative studies, the two new stereocenters formed by addition across the double bond are set independently and influenced by different factors. These findings suggest a stepwise process via an intermediate capable of lactone closure with either stereochemistry, in contradistinction to the more familiar scenario in which anti addition is dictated by a bridging chloronium ion intermediate.
Catalytic enantioselective halolactonization of enynes and Alkenes
Zhang, Wei,Liu, Na,Schienebeck, Casi M.,Decloux, Kyle,Zheng, Suqing,Werness, Jenny B.,Tang, Weiping
experimental part, p. 7296 - 7305 (2012/07/03)
New organocatalysts have been developed for the enantioselective halolactonization 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 enyne halolactonization, a second generation of catalysts was designed for simple olefins. Up to 91%ee was observed for chlorolactonization of 1,1-disubstituted alkenes. The catalysts developed for the enantioselective halolactonization of both enynes and alkenes are composed of a cinchona alkaloid skeleton tethered to a urea group.
