INDOLES .11. SYNTHESES AND STEREOCHEMISTRY OF 5,6,7,8,13,13B-HEXAHYDROBENZ[A]INDOLO[2,3-H]QUINOLIZINES AND OF 5,6,7,8,13,13B-HEXAHYDRO-14H-BIS-INDOLO[3,2-A][2,3-H]-QUINOLIZINE

A new and efficient synthesis of substituted 5,6,7,8,13,]3b-hexahydro-benz[a]indolo[2,3-h]quinolizines (5b,d) via lactamisation of dihydropyrano[3,4-b]indol-1-one (3), cyclisation with phosphorus oxychloride and reduction with sodium borohydride is described. The unsubstituted 5,6,7,8,13,13b-hexahydro benz[a]indolo[2,3-h]quinolizine (5) is prepared by analogy starting with the lactamisation of isochromanone with tryptamine. The unsubstituted 5,6,7,8,13,13b-hexahydro-14H-bisindolo[3,2-a][2,3-h]quinolizine (9) is synthesized by lactamisafion of 3 with tryptamine, cyclisation and again reduction of the intermediate immonium salt. The stereochemistry of the unsubstituted quinolizine derivatives is investigated by H-1-, C-13-nmr-, NOE spectroscopy and by X-ray analysis.