The Nature of Cyclopentyne from Different Precursors
摘要:
The ratio of [2+2] and [2+4] cycloaddition products from reaction of spiro[4.2]hepta-1,3-diene with cyclopentyne depends on the source of the cyclopentyne. A mechanistic rationale for the phenomenon is presented. (C) 1997 Elsevier Science Ltd.
Cyclopentyne, as generated from dibromomethylenecyclobutane, a formerly unknown cyclopentyne source, undergoes [2+2]-cycloadditions with various substituted olefins yielding bicyclo[3.2.0]hept-1(5)-ene derivatives.
Competitive Intermolecular Pericyclic Reactions of Free and Complexed Cyclopentyne
作者:John C. Gilbert、Duen-Ren Hou
DOI:10.1021/jo0352880
日期:2003.12.1
Intermolecular competition for cyclopentyne by different alkenes supports the hypothesis that organolithium-promoted decomposition of precursors to cyclopentyne affords one or more lithium-ion-complexed species. Competition reactions with mixtures of 2,3-dihydropyran do not clearly differentiate between complexed and unencumbered (free) forms of cyclopentyne, but those involving spirodiene 2 and cyclohexene do. Remarkably, the cycloaddition reactions of free cyclopentyne are not diffusion-controlled despite its high reactivity.