Thermal Reactions of N-Acyl Phenylcyclobutylimines

Article abstract of DOI:10.1002/jccs.199800030

Flash vacuum thermolysis of the parent and phenyl substituted N-acyl cyclobutylimines 3 was under investigation. At 500 °C and 0.01 torr, 3d with phenyl group on C-1 and 3e with phenyl group on C-2 of cyclobutane ring underwent ring expansion processes to produce N-acyl 1,2,3,4-tetrahydropyridines 8d and 8e. Meanwhile the parent N-acyl cyclobutylimines 3a together with the phenyl group on C-3 (3c) and imine carbon (3b) proceeded a hydrogen shift reaction to afford N-acylaminomethylenecyclobutanes 8a-c. In addition, cycloreversion competed with ring expansion or hydrogen shift in all cases.