Regioselective Carbonylative Heteroannulation of o-Iodothiophenols with Allenes and Carbon Monoxide Catalyzed by a Palladium Complex: A Novel and Efficient Access to Thiochroman-4-one Derivatives
摘要:
The palladium-catalyzed carbonylative ring-forming reactions of 2-iodothiophenol, and the corresponding substituted derivatives, with allenes and carbon monoxide are described. The reactions afford thiochroman-4-ones in good to excellent isolated yields with quite high regioselectivity. The catalytic heteroannulation may involve regioselective addition of the sulfur moiety of the reactants on the more positive end of the allene, arylpalladium formation, CO insertion, subsequent intramolecular cyclization, and then reductive elimination. The regioselectivity is probably governed by electronic effects.
STRUCTURAL STUDIES OF A NOVEL HETEROCYCLIC PHOSPHORANE
作者:Christopher D. Gabbutt、John D. Hepworth、B. Mark Heron、Alan M. Jones、Eric S. Raper、William Clegg
DOI:10.1080/10426509808045499
日期:1998.12.1
Reaction of 2,2,6-trimethylthiochroman-3,4-dione with an excess of methylenetriphenyl-phosphorane yields the stabilised ylide (4) by way of an alpha -ketol rearrangement. X-Ray crystallography indicates that (4) exists as the (Z)-isomer and provides supporting evidence for an enolate structure.