The synthesis of caprolactam derivatives substituted at C4, C5, C6 and C7 with alkyl, aryl, acyl and hetero substituents is described. A variety of synthetic approaches to these compounds have been investigated and assessed, particularly for the synthesis of C4- and C6-substituted compounds. A significant number of the C4-, C6- and C7- substituted compounds prepared show central nervous system activity, ranging from convulsants to depressants depending on the position and nature of the substituent group.
A series of allyloxy unsaturated tetrahydroazepinones has been prepared and their Claisen rearrangements have been investigated. The 4-allyloxy compounds (4a-e) rearranged thermally to give the 3-substituted hexahydro derivatives (9). In some cases further reaction products were obtained, particularly when higher temperatures were used. Rearrangement of the 4-propargyloxy system (4f) proved more complicated, and N-allyl-2,3,4,5-tetrahydro-1H-azepin-2-one derivatives (21a,b) were unreactive. Alkylation of the hexahydroazepine-2,4-dione system (3) with various allyl halides gave mixtures of the 3-mono-(20) and the 3,3-di-substituted (19) products. The unsaturated ethers generally showed marked muscular depression on the central nervous system of mice, while their rearrangement products were only weakly depressant.