Different Reactivity Patterns of Trimethylsilyl- and Phenyl-Substituted Propargylallenes: Fe2(CO)9- and [Ag]+-Promoted Cyclizations

Thermolytic rearrangement of the diphenyl-propargylallene [3,3-(biphenyl-2,2′-diyl)-1-phenyl-1-{9-[(phenylethynyl]-9H-fluorenyl}allene], 9, yields the bis-fluorenyliden-bis-allene 10, which undergoes electrocyclization to form 3,4-di(fluorenyliden)-1,2-diphenylcyclobutene, 12, in which the overlapping fluorenylidenes give rise to C 2 symmetry. The propargylallene 9 reacts with iron carbonyls to form 15, in which an (η5-fluorenyl)Fe(CO)2 moiety …