3 4 this could be applied to acylsilanes of type I (Scheme I), then a versatile route to benzocyclobutene systems required for our anthracyclinone studies would be a~ ailable.~ We report here the products from thermal and photochemical activation of acylsilane 1. Vacuum pyrolysis of la at 450" C through a quartz tube filled with quartz chips cleanly afforded one isolable product in 70% yield. s Spectroscopic and analytical data suggest ...