Studies in the cycloproparene series: Formation of a new dimer of 1H-cyclopropa[b]naphthalene

1-(Trimethylsilyl)-1H-cyclopropa[b]naphthalene (10) and its 1-methyl deriva tive (11) have been isolated as pure compounds from use of a lipophilic siz e exclusion gel. Acylation of the 1H-cyclopropa[b]naphthalenyl anion (2) is erected with N,N-dimethyl-benzamide and -acetamide to give (5) and (6), re spectively. Analogous reactions with the 1-(trimethylsilyl)-1H-cyclopropa[b ]naphthalenyl anion (9) do not yield the 1-acyl-1-(trimethylsilyl)-1H-cyclo propa[b]naphthalenes (12) and (13); instead the novel 6-methyl-7H-dibenzo[b ,g]fluorene (15) results from attempted acetylation. Compound (15), a forma l dimer of 1H-cyclopropa[b]naphthalene (1), is formed also from anion (9) b oth in toluene and from addition of hydrocarbon (1); its structure is assig ned from spectroscopic data and confirmed by single-crystal X-ray analysis.