Stereochemistry of nitrogen heterocycles. 49. Synthesis and transformations of stereoisomeric 4-keto-2-methyl-n-chloro-trans-decahydroquinolines

Abstract Epimeric (with respect to the methyl group) stereoisomers of 4-keto-2-methyl-1-chloro-trans-decahydroquinoline were obtained, and their transformations under the influence of triethylamine were investigated. It was shown that the direction of the transformations depends on the steric orient...
Ausführliche Beschreibung

Abstract Epimeric (with respect to the methyl group) stereoisomers of 4-keto-2-methyl-1-chloro-trans-decahydroquinoline were obtained, and their transformations under the influence of triethylamine were investigated. It was shown that the direction of the transformations depends on the steric orientation of the methyl group and the molar ratio of the N-chloroamine and triethylamine. The N-chloroamine isomer with an equatorial methyl group undergoes dehydrochlorination in the presence of excess triethylamine to give 2-methyl-4-hydroxy-trans-5,6,7,8,9,10-hexahydroquinoline. With an equimolar amount of triethylamine in solution in CCl4 the principal reaction pathway becomes dehydrochlorination and subsequent chlorination to give 2-methyl-4-hydroxy-3-chloro-trans-5,6,7,8,9,10-hexahydroquinoline. The N-chloroamine isomer with an axial methyl group in the presence of both excess and, in particular, equimolar amounts of triethylamine undergoes, in addition to dehydrochlorination and chlorination in the β position of the piperidine ring, cis-trans isomerization and subsequent dehydrogenation with the primary formation of 2-methyl-4-hydroxy-3-chloro-5,6,7,8-tetrahydroquinoline. The mechanism of the transformations is examined. Ausführliche Beschreibung