Alkynones react with arylboronic acids in the presence of a rhodium(I) catalyst to afford four- and five-membered-ring cyclic alcohols equipped with a tetrasubstituted exocyclic olefin. The cyclic allylic alcohol skeleton is constructed by the carbon-carbon bond formation between the carbonyl group and an alkenylrhodium(I) intermediate formed by the regioselective addition of an arylrhodium(I) species across the carbon-carbon triple bond. (c) 2007 Elsevier Ltd. All rights reserved.
Acyl 1,3-Migration in Rhodium-Catalyzed Reactions of Acetylenic β-Ketoesters with Aryl Boronic Acids: Application to Two-Carbon-Atom Ring Expansions
Synthesis of (±)-Gymnomitrol. Mn(OAc)<sub>3</sub>-Initiated Free-Radical Cyclization of Alkynyl Ketones
作者:Steven V. O'Neil、Cheri A. Quickley、Barry B. Snider
DOI:10.1021/jo9622338
日期:1997.4.1
Mn(OAc)(3)-initiated cyclization of alkynyl ketones in 9-19:1 EtOH/HOAc at 90 degrees C is a useful cyclization procedure in favorable cases. Cyclization of (trimethylsilyl)alkynyl ketone 4e provides 62% of silylalkenes 26 and 27 in the key reaction of a seven-step (16% overall yield) synthesis of gymnomitrol (1) from readily available ketone 23. 9alpha-Hydroxygymnomitryl acetate (2) and 9-oxogymnomitryl