Studies in the Cycloproparene Series: Unexpected Products from Peterson Olefinations

Article abstract of DOI:10.1002/ejoc.200300382

Reaction of tetraphenylcyclopentadienone with anion 8 derived by monodesilylation of 1,1-bis(trimethylsilyl)cyclopropa[b]naphthalene (10) gives the 1-(5′-cyclopentadienyl)-substituted cycloproparene 17 from simple anion addition to the carbonyl group rather than fulvalene 16 from loss of Me₃SiO^-. Reactions of anion 8 with p-(trifluoromethyl)benzaldehyde and thiophene-2-carbaldehyde give the expected exocyclic olefins 12a and 12b, respectively. In contrast, the 3,6-dimethoxy analogue 24, obtained from cycloproparene 20, gives the C1 unsubstituted cycloproparene 19 and the Tishchenko products, p-(trifluoromethyl)benzyl p-(trifluoromethyl)benzoate (21) and 2-thienylmethyl thiophene-2-carboxylate (22), respectively. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.