Stereospecific reduction of 1,4,5,6-tetrahydrobenzo[f]quinolin-3(2H)-ones with triethyl-silane-trifluoroacetic acid

Article abstract of DOI:10.1055/s-1993-26018

β-Tetralone pyrrolidine enamines 6 react with acrylamine to produce mixtures of double bond positional isomeric tetrahydrobenzo[f]quinolin-3(2H)-ones, e.g. 3, 11, 12. Each of these isomers is reduced stereoselectively by triethylsilane-trifluoroacetic acid to the cis- or trans-fused octahydrobenzo[f]quinolone system, e.g. 4, 5. It is established that reported failures to prepare pure trans-fused product 5 by this reductive method is due to the heterogeneity of the product of the β-tetralone enamine-acrylamide reaction, and not to a defect in the reducing reagent system.