STEREOSPECIFIC REDUCTION OF 1,4,5,6-TETRAHYDROBENZO[F]QUINOLIN-3(2H)-ONES WITH TRIETHYLSILANE TRIFLUOROACETIC-ACID

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