Studies in the Cycloproparene Series : Unexpected Products from Peterson Olefinations

Reaction of tetraphenylcyclopentadienone with (1H-cyclopropa[b]naphthalen-1-yltrimethyl)silane anion [derived by monodesilylation of 1,1-bis(trimethylsilyl)cyclopropa[b]naphthalene] gives the 1-(5'-cyclopentadienyl)substituted cycloproparene from simple anion addn. to the carbonyl group rather than fulvalene from loss of Me3SiO-. Reactions of (1H-cyclopropa[b]naphthalen-1-yltrimethyl)silane anion with p-(trifluoromethyl)benzaldehyde and thiophene-2-carboxaldehyde give the expected exocyclic olefins, 1-[[3-(trifluoromethyl)phenyl]methylene]-1H-cyclopropa[b]naphthalene and 2-(1H-cyclopropa[b]naphthalen-1-ylidenemethyl)thiophene. In contrast, 3,6-dimethoxy-1H-cyclopropa[b]naphthalen-1-yltrimethylsilane anion, obtained from a cycloproparene deriv., gives a C1 unsubstituted cycloproparene and Tishchenko products, p-(trifluoromethyl)benzyl p-(trifluoromethyl)benzoate and 2-thienylmethyl 2-thiophenecarboxylic acid 2-thienylmethyl ester.