Enantioselective tandem formation and [2,3]‐sigmatropic rearrangement of cyclic propargylic oxonium ylides catalyzed by dirhodium(II) tetrakis[<i>N</i>‐phthaloyl‐(<i>S</i>)‐<i>tert</i>‐leucinate]
rearrangement of propargylic oxonium ylides generated by catalytic diazo decomposition. Catalysis of α-diazo-ß-keto esters 4a—g using dirhodium(II) tetrakis[N-phthaloyl-(S)-tert-leucinate] in toluene has led to the virtually exclusive formation of benzofuran-3-ones bearing an allenic group with up to 79% ee.
Palladium-Catalyzed Cyclization of Alkynoic Acids To Form Vinyl Dioxanones Bearing a Quaternary Allylic Carbon
作者:Yohei Ogiwara、Kazuya Sato、Norio Sakai
DOI:10.1021/acs.orglett.7b02572
日期:2017.10.6
A palladium-catalyzed intramolecular reaction of carboxylic acids and alkynes in a novel cyclization manner was developed. This unique cyclization efficiently provided a wide range of complex ring systems—vinyl dioxanones bearing a quaternary allylic carbon. Mechanistic studies suggest an allenyl carboxylate as an intermediate.