Studies on Indenopyridine Derivatives and Related Compounds. III. Stereochemistry of 1-Substituted 4, 9-Dihydroxy-9-phenyl-1, 2, 3, 4, 4a, 9a-hexahydro-9H-indeno [2, 1-b] pyridines

Reaction of 1-methyl- or 1-benzyl-9-phenyl-1, 2, 3, 4-tetrahydro-9H-indeno [2, 1-b] pyridin-4-ones (1a and 1b) with potassium hydroxide in 1-propanol gave the 9-hydroxy derivatives (4a and 4b) in good yield. Sodium borohydride reduction of 4a gave the B/C-cis-4, 9-dihydroxy-1, 2, 3, 4, 4a, 9a-hexahydro-9H-indeno [2, 1-b] pyridine (8) stereospecifically. On the other hand, 4b gave the B/C-trans-4, 9-dihydroxy-1, 2, 3, 4, 4a, 9a-hexahydro-9H-indeno [2, 1-b] pyridine (10) and its C-9 isomer (11). Treatment of 11 with acetic anhydride in pyridine gave the corresponding monoacetate 13. However, acetylation of 10 afforded the B/C-cis monoacetate 12 with isomerization at B/C ring juncture. The structure and stereochemistry of these compounds is discussed.