The solvolysis in acid solution of allylic halides and acetates of methylenecyclopropanes and cyclopropylmethanes does not lead to ring opening when there is an ethoxycarbonyl substituent on the ringmethylene. Only the cyclopropenyl derivative is obtained. A study of the electronic structure and the geometry of the possible allylic cation intermediate has been carried out using the MNDO method. In
The synthesis of the highly reactive 1,4-unsymmetrically substituted butatrienes 12a-c is described. When employing a strict synthetic protocol, these alkatrienes react with lithium metal to 3,4-dilithio-1,2-butadienes 20a-c as stable intermediates. The structure of 20 is supported by IR and NMR spectroscopic evidence. The same dianionic intermediate can be prepared in one case by double deprotonation
Allenes. Part XV. The addition of dihalocarbenes to allenes and conversion of 1,1-dihalo-2-methylenecyclopropanes to cumulenes
作者:W. J. Ball、S. R. Landor、N. Punja
DOI:10.1039/j39670000194
日期:——
The addition of dichloro- and dibromo-carbenes to the more substituted double bond of five different allenes gave 1,1-dichloro- and 1,1-dibromo-2-methylenecyclopropanes. Some of these have been converted by means of n-butyl lithium to cumulenes.