Bridged-ring nitrogen compounds. Part 5. Synthesis of 2,6-methano-3-benzazonine ring-systems

Abstract

Syntheses of cis- and trans-4-benzyl- and 4-(3-methoxybenzyl)-2-methoxycarbonyl-1-methylpiperidines are described; amino-acids and amino-alcohols obtained from these compounds failed to cyclise. cis-2-Benzyl-4-ethoxycarbonyl-1-methylpiperidine has been made and its amino-acid hydrochloride cyclised in polyphosphoric acid at 160 °C to give 2,4,5,6,7-hexahydro-3-methyl-2,6-methano-1H-3-benzazonin-7-one which was converted into several derivatives. 4-Benzyl-4-ethoxycarbonyl-1-methylpiperidine, obtained by two routes, was hydrolysed and cyclised to give N-methylspiro[indane-2,4′-piperidine]-1-one which was also converted into several derivatives.