Rearrangements of 4-alkynyl-, 4-alkenyl-, and 4-alkyl-4-hydroxy-3-methylenecyclobutenes
摘要:
Reported here are the thermal rearrangements of the 4-alkynyl- (1), 4-alkenyl- (7), and 4-alkyl-4-hydroxy-2-methyl-1-phenyl-3-benzylidenecyclobutene (11) to, respectively, the phenol 5, derived from the p-quinonemethide 4, the benzylidenecyclohexenone 10, and the acyclic dienone 14.
Rearrangements of 4-alkynyl-, 4-alkenyl-, and 4-alkyl-4-hydroxy-3-methylenecyclobutenes
摘要:
Reported here are the thermal rearrangements of the 4-alkynyl- (1), 4-alkenyl- (7), and 4-alkyl-4-hydroxy-2-methyl-1-phenyl-3-benzylidenecyclobutene (11) to, respectively, the phenol 5, derived from the p-quinonemethide 4, the benzylidenecyclohexenone 10, and the acyclic dienone 14.
Synthesis of o-quinodimethanes and benzocyclobutenes from dimethyl squarate
作者:John E. Ezcurra、Harold W. Moore
DOI:10.1016/s0040-4039(00)73703-8
日期:1993.9
Selected 3-alkylidene(and benzylidene)-4-allenylcyclobutenes were shown to undergo an unusual thermal ring expansion to o-quinodimethanes and thus to benzocyclobutenes upon electrocyclic ring closure. The mechanism of this rearrangement is envisaged to involve ring opening of the starting cyclobutenes to the corresponding octa-1,2,4,6,7-pentaenes which lead to the quinodimethanes upon ring closure