Structural factors for the formation of propellane-type products in the solvolysis of bicyclic bridgehead compounds

Methanolyses of 2-oxobicyclo[3.3.1]non-1-yl triflate, 3,3-dimethyl-2-oxobic yclo[3.3.1]non-1-yl triflate, and 2-oxobicyclo[4.3.1]dec-1-yl mesylate gave the corresponding propellanone in 12%, 20%, or 3.2% yield, respectively, b eside substitution or rearranged products under typical conditions. No prop ellane-type product was obtained in the solvolyses of 1-bromobicyclo[3.3.1] nonane, 2-methylidenebicyclo[3.3.1]non-1-yl heptafluorobutyrate, and 3,3-di methyl-2-thioxobicyclo[3.3.1]non-1-yl tosylate. The factors that permit the formation of the propellane-type product from the intermediate bridgehead cations are examined with the aid of theoretical calculations at PM3 and B3 LYP/6-31G*.