期刊
TETRAHEDRON
卷 69, 期 52, 页码 11197-11202出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.tet.2013.10.080
关键词
Carbonylative cyclization; Cobalt carbonyl catalyst; Butenolide synthesis; Internal alkyne; Double carbonylation
资金
- Japan Society for the Promotion of Science
- [2510638]
Despite the fact that many transition-metal-catalyzed reactions of organosulfur compounds with internal alkynes are ineffective, cobalt carbonyl (Co-2(CO)(8)) is an excellent catalyst for carbonylative cyclization of internal alkynes with carbon monoxide. When Co-2(CO)(8)-catalyzed reactions of internal alkynes with organic thiols are conducted in acetonitrile under 4 MPa pressure of carbon monoxide, thiolative lactonization of internal alkynes successfully takes place with incorporation of two molecules of CO. This carbonylation provides a useful tool to prepare the corresponding alpha,beta-unsaturated gamma-thio-gamma-lactones (butenolide derivatives) in good yields. In the cases of unsymmetrical alkynes, such as 2-octyne and 6-methyl-2-heptyne, the thiolative lactonization proceeds with moderate regioselectivity to give the butenolide derivatives on which the carbonyl group preferentially bonds to the less hindered acetylenic carbon. Mechanistic pathways about the present thiolative lactonization are also discussed. (C) 2013 Elsevier Ltd. All rights reserved.
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