138235-95-7Relevant academic research and scientific papers
Torquoselectivity in the electrocyclic conversion of benzocyclobutenes to o-xylylenes
Jefford, Charles W.,Bernardinelli, Gerald,Wang, Ying,Spellmeyer, David C.,Buda, Andrzej,Houk
, p. 1157 - 1165 (1992)
The conrotatory electrocyclic opening of benzocyclobutene to o-xylylene was studied by means of ab initio molecular orbital calculations. The theory developed earlier to predict the torquoselectivity of ring opening of 3-substituted cyclobutenes was found to be applicable. Experimentally, the ring opening of several 7-substituted benzocyclobutenes, such as the cyano, methoxycarbonyl, and formyl derivatives was examined. o-Xylylenes were obtained in which cyano or ester groups had rotated outwards, whereas the formyl group turned inwards. N,N-Dimethylbenzocyclobutene-7-carboxamide exhibited 75% inward torquoselectivity upon ring opening. A reversal of mode was seen with the 7-methyl derivatives of benzocyclobutene-7-carbonitrile and methyl benzocyclobutene-7-carboxylate in that the 7-methyl substituent manifested overwhelming outward motion.
