Bridged-ring nitrogen compounds. Part 6. Synthesis of the 2,5-methano-3-benzazocine ring-system

Abstract

A novel synthesis of 8,8-bisethoxycarbonyl-6,7,8,9-tetrahydrobenzocyclohepten-5-one and its 2-methoxy-analogue is presented. Each was converted into the corresponding 8-carboxy-6,7,8,9-tetrahydrobenzocyclohepten-5-one which were converted into amides and thence by way of 6-bromoketoamides to the keto-lactams: 2-benzyl-1,2,3,4,5,6-hexahydro-2,5-methano-3-benzazocine-1,4-dione and 1,2,3,4,5,6-hexahydro-8-methoxy-3-methyl-2,5-methano-3-benzazocine-1,4-dione. These, in turn, were reduced via lactams to 3-benzyl-1,2,3,4,5,6-hexahydro-2,5-methano-3-benzazocine and 1,2,3,4,5,6-hexahydro-8-methoxy-3-methyl-2,5-methano-3-benzazocine respectively.