Study of the substituted vinylallene-methylenecyclobutene electrocyclic equilibria. Comparison with the butadiene-cyclobutene and bisallene-bismethylenecyclobutene electrocyclic equilibria
Study of the substituted vinylallene-methylenecyclobutene electrocyclic equilibria. Comparison with the butadiene-cyclobutene and bisallene-bismethylenecyclobutene electrocyclic equilibria
Photochemistry of organic nitrogen compounds. Part III. The formation of allenes and 1,3-dienes from pyrazolenines: a photochemical reaction involving ion-pairs
作者:A. C. Day、M. C. Whiting
DOI:10.1039/j29670000991
日期:——
The photolysis of pyrazolenines normally gives cyclopropenes via a vinyldiazoalkane; but, in the present work 3-(1′-acyloxyalkyl)-5,5-dimethylpyrazolenines have been found to give allene and 1,3-diene esters in good yield, together with small quantities of a vinylallene. Attempts to trap an intermediate diazoalkene by photolysis in the presence of acid were not successful, leading merely to partial
1-dibromo-2-vinylcyclopropane derivatives with MeLi yielded cyclopentadienes as the main products together with small amounts of allenic compounds (Table 1). By the same reaction 2,2,2′,2′-tetrabromobicyclopropyl derivatives yielded, in all but one case, only small amounts of diallenes; the exception is the exclusive formation of 2,7-dimethyl-2,3,5,6-octatetraene, (XIII) from2,2,2′,2′-tetrabromo-3,3,3′,
3,4-Dilithio-2,5-dimethyl-2,4-hexadiene (4a) rearranges to the cross-conjugated 2,5-dimethylhexadienediyl dianion 11a. A mechanistic investigation proves the intermolecularity of this rearrangement, which is also observed when starting from 4b. The 3-lithio-2,5-dimethylhexadienyl anion Ipa with one vinyllithium and one allyllithium group, is a true intermediate in this rearrangement, its synthetic potential is employed in the reaction with dichlorosilanes to form 2-isopropylidene-2,5-dihydrosilols 8.
VOSKANYAN M. G.; PASHAYAN A. A.; BADANYAN SH. O., AJKAKAN KIMIAKAN AMSAGIR, ARM. XIM. ZH., 1978, 31, HO 10 750-756
作者:VOSKANYAN M. G.、 PASHAYAN A. A.、 BADANYAN SH. O.