Cyclopropylethylenes have been prepared by Wittig reactions, by coupling of dicyclopropylcarbene, and by dehydration of a suitably substituted ethanol. The scope and limitations of these preparations are discussed, particularly with regard to the synthetic application of the Wittig reaction to tetrasubstituted ethylenes.
A rapidly reversible degenerate cope rearrangement
作者:W. von E. Doering、W.R. Roth
DOI:10.1016/s0040-4020(01)99207-5
日期:1963.1
The occurrence of a structurally degenerateCoperearrangement which proceeds rapidly at room temperature is revealed by the examination, at varying temperatures, of the N.M.R. spectrum of bicyclo[5.1.0]octa-2,5-diene (I). This molecule is made by the cyclopropanation of cycloheptatriene in the 3, 4 position according to Gaspar-Roth. Its structure is assigned by virtue of its conversion to bicyclo[5
Preferential Incorporation of a Cyclopropyl σ Bond Over an Ethylenic π Bond in the TCNE Cycloaddition of 1,2-Dicyclopropylethylene. Occurrence of the Type-II Reaction in Some Disubstituted Substrates
Among the two types of cycloadditions known to take place in the reactions of cyclopropyl-substituted ethylenes (1) with tetracyanoethylene (TCNE) (type-1 gives a cyclobutane derivative (2) and type-II yields a vinylcyclopentane derivative (3), the type-II reaction has been practically limited to occur in reactions of tetrasubstituted substrates. However, some disubstituted substrates, namely cis-
在低极性溶剂中产生少量3;然而,II 型从未成为一个主要过程。母体乙烯基环丙烷未能在所有物质中产生 II 型加合物
The u.v. spectra of 1,1-dicyclopropyl-, cis- and trans-1,2-dicyclopropyl-, and tricyclopropylethylene, prepared by Wittig reactions, and tetracyclopropylethylene, isolated from decomposition products of dicyclopropyl ketone toluene-p-sulphonhydrazone sodium salt in dry diglyme have been studied.
Pauson-Khand Carbonylative Cocyclizations of Acetylenes with Cyclopropylallenes
作者:Armin de Meijere、Bernard Cazes、Mohammed Ahmar、Mario Knoke
DOI:10.1055/s-2007-965882
日期:2007.2
The Pauson-Khand-like carbonylative cocyclizations of alkynes with cyclopropylallene and with 1,3-dicyclopropylallene occur regioselectively and lead to 4-(cyclopropylmethylene)cyclopentenones (43-59% for six examples).