SCOPE AND LIMITATIONS OF THE FLASH VACUUM THERMOLYSIS APPROACH TO SMALL PARACYCLOPHANES

Article abstract of DOI:10.1016/S0040-4020(01)87572-4

Flash vacuum thermolysis (FVT) of 3-methylene-6-spirocyclohexa-1,4-dienes (2) was investigated as a synthetic approach to small paracyclophanes 1 (1a, n=8; 1b, n=7; 1c, n=6).The method was found to be preparatively attractive for 1a (80percent yield), less so for 1b (7percent useful yield), and not at all for 1c which was too unstable to survive the conditions of its formation.Besides 1, p-alkylstyrenes (3) and 2-methylbenzocycloalkenes (4) were obtained; the total recovery of monomeric products was good (60-85percent).The temperature dependence of product formation furnished useful information on the mechanisms of formation and decomposition of 1 under the conditions of FVT.