Studies in the cycloproparene series: formation of a new dimer of 1H-cyclopropa[b]naphthalene.
1-(Trimethylsilyl)-1H-cyclopropa[b]naphthalenes (I; R = SiMe3; R1 = H, Me) have been isolated as pure compds. with use of a lipophilic size exclusion gel. Acylation of the 1H-cyclopropa[b]naphthalenyl anion is effected with N,N-dimethylbenzamide and -acetamide to give, resp., (I; R = COPh, COMe; R1 = H). Analogous reactions with the 1-(trimethylsilyl)-1H-cyclopropa[b]naphthalenyl anion (II) do not yield the 1-acyl-1-(trimethylsilyl)-1H-cyclopropa[b]naphthalenes; instead the novel 6-methyl-7H-dibenzo[b,g]fluorene (III) results from attempted acetylation. III, a formal dimer of 1H-cyclopropa[b]naphthalene (IV), is formed also from anion II both in toluene and via addn. of IV; its structure is assigned from spectroscopic data and confirmed by single-crystal x-ray anal.
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