Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
Beilstein J Org Chem. 2010 Apr 8;6:33. doi: 10.3762/bjoc.6.33.
The synthesis of C3-carbocyclic spirooxindoles was realized by way of an intramolecular [2 + 2] cycloaddition reaction between a vinylidene indolin-2-one and an alkyne. The cycloaddition reaction occurs selectively with the distal double bond of the allene, is tolerant of a phenyl and trimethylsilyl group on the terminus of the alkyne, and can be used to access bicyclo[4.2.0]octadienes and bicyclo[5.2.0]nonadienes. The allene precursors are not observed, but are likely intermediates of an infrequently encountered thermal [3,3]-sigmatropic rearrangement of a propargylic acetate.
C3-碳环螺环氧化吲哚的合成立足于乙烯基二酮与炔烃之间的分子内[2+2]环加成反应。此环加成反应具有选择性，仅与丙二烯的远端双键发生反应，且对炔烃末端的苯基和三甲基硅基具有容忍性，可用于构建双环[4.2.0]辛二烯和双环[5.2.0]壬二烯。虽然无法观察到丙二烯前体，但它们很可能是丙炔酸酯罕见的热[3,3]-σ重排反应的中间体。
