SYNTHESIS OF BRIDGEHEAD-SUBSTITUTED BICYCLO[2.2.1]HEPTANES - RADICAL CYCLIZATION OF AN OXIME ETHER AND AN ALPHA,BETA-UNSATURATED ESTER

The synthesis of bicyclo[2.2.1]heptanes with useful functionality at e ach bridgehead is achieved by radical cyclization of appropriately sub stituted 4-methylene- and 4-benzyloxyimino-cyclohexylmethyl radicals. The latter process, for example, leads to a bridgehead amine. Optimum yields are achieved when the reactions are conducted at 110-degrees wi th slow addition of tributyltin hydride; under these conditions, the u ncyclized isomer is either not detected, or formed in very small quant ity. Production of a mixture of five- and six-membered cycloalkanones from similar treatment of the analogous 4-oxocyclohexylmethyl radicals reveals that the reaction is medicated by the corresponding 1-norborn yloxy radical.