Cyanogen-Bromide-Mediated and Methyl-Chloroformate-Mediated Synthesis of Some [3]Benzazonino[8,7,6-abc]Carbazole, [3]Benzazecino[9,8,7-abc]Carbazole, Naphth[1,8,7-def]Azonine and Naphth[1,8,7-def]Azecine Derivatives

Abstract

Reaction of 7,8-dimethoxy-1,4,5,9,13c,13d-hexahydro-2H-indolo [3′,2′:4,5] indolo [1,7,6-aji] isoquinoline (4a) and 8,9-dimethoxy- 1,2,3,5,6,10,14c,14d-octahydro-indolo[3′,2′:3,4] naphtho [2,1,8-ija] quinolizine (4b) with cyanogen bromide in the presence of potassium carbonate afforded the elimination products 7,8-dimethoxy-1,2,3,4,5,9- hexahydro [3] benzazonino [8,7,6-abc]carbazole-3-carbonitrile (5a) and 8,9-dimethoxy-2,3,4,5,6,10-hexahydro-1H-[3] benzazecino [9,8,7-abc]carbazole-4-carbonitrile (5b) in 4% and 88% yield respectively; 7- (2-bromo)ethyl-1,2-dimethoxy-4,5,6,6a,7,12-hexahydroisoquino[8,1-ab ]carbazole-6-carbonitrile (6a) was also isolated in 20% yield from the former reaction. Products of analogous structure were also obtained from (4a,b) when methyl chloroformate was used in place of cyanogen bromide. Reaction of (4b) with cyanogen bromide in the presence of water and magnesium oxide afforded the solvolysis product 14d-hydroxy-8,9-dimethoxy-2,3,4,5,6,10,14d,14d-octahydro-1H-[3] benzazecino [9,8,7- abc ]carbazole-4-carbonitrile (8b) together with (5b). Similarly application of this reaction to 8,9-dimethoxy-2,3,5,6,11a,11b-hexahydro-1H-naphtho[2,1,8-ija] quinolizine (1b) afforded both the corresponding solvolysis and elimination products; (4a) and 7,8- dimethoxy-1,2,4,5,10a,10b-hexahydronaphtho[1,8,7-ghi] indolizine (1a), however, gave only solvolysis products. Solvolysis and elimination products were also isolated when (1b) and (4b) were subjected to cyanogen -bromide-mediated methanolysis reactions. Acid-catalysed elimination reactions of the alcohol solvolysis products are described along with reaction of some of the elimination products with lithium tetrahydroaluminate.