Synthesis of 3a,4,6,7,11b,12-hexahydro-3a-methyl-7-phenylbenzo[a]furo[2,3-g]quinolizines

By alkylation of stereoisomeric 7a-methyl-2-oxo-5-phenylfuro-[2,3-c]piperidines with phenacyl bromide and subsequent reduction of the keto group by sodium borohydride, amino alcohols were obtained; heating of these products in 70% sulfuric acid affords 3a,4,6,7,11b,12-hexahydro-3a-methyl-7-phenylbenzo[a]furo[2,3-g]quinolizines. It was found that the cis-quinolizidine, upon heating to 150°C in acetic acid, is isomerized to the trans-quinolizidine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1679–1682, December, 1993.