Synthesis and Reactions of 4-cis- and 4-trans-Hydroxy-2e-methyl-4-ethynyl-trans-decahydroquinolines

By treating 2e-methyl-4-oxo-trans-decahydroquinoline with lithium acetylide a mixture of stereoisomeric 4-cis-hydroxy-2e-methyl- and 4-trans-hydroxy-2e-methyl-4-ethynyl-trans-decahydroquinolines was obtained in 3:2 ratio. Their reaction with acetonitrile in the presence of sulfuric acid (Ritter's reaction) results in a mixture of stereoisomeric 4-cis-acetylamino-2e-methyl- and 4-trans-acetylamino-2e-methyl-4-ethynyl-trans-decahydroquinolines in the same ratio. The ethynyl group of alcohols synthesized is not hydrated under conditions of Kuchrerov's reaction. The boiling of the alcohols with formic acid furnished a mixture of 4-acetyl-2e-methyl and 2e-methyl-4-ethynyl-1,2,3,6,7,8,9,10-octahydroquinolines in 1:7 ratio. The former of these compounds under conditions of Ritter's reaction yielded a mixture (1:1.4) of stereoisomeric 4-acetyl-4-trans-acetylamino- and 4-acetyl-4-cis-acetylamino-2e-methyl-trans-decahydroquinolines. From 2e-methyl-4-ethynyl-1,2,3,6,7,8,9,10-octahydroquinoline under the same conditions were obtained both already mentioned stereoisomeric 4-acetylamino-2e-methyl-4-ethynyl-decahydroquinolines (53% of cis-isomer and 35% of trans-isomer in the mixture) and 4-acetyl-4-acetylamino-2e-methyldecahydroquinolines (7% of cis-isomer and 5% of trans-isomer).