CYCLIC ALLYLAMINE/ENAMINE SYSTEMS-6 SOME REACTIONS OF 4-(INDOL-2-YLCARBONYL)-, 4-(INDOL-3-YLCARBONYL)- AND 4-(INDOL-3-YLMETHYL)-1,2,5,6-TETRAHYDRO-1-METHYLPYRIDINES

Article abstract of DOI:10.1016/0040-4020(84)85021-8

Indol-3-yl 1-methyl-1,2,5,6-tetrahydropyridin-4-yl ketone (1d) can be isomerised to indol-3-yl 1-methyl-1,2,3,4-tetrahydropyridin-4-yl- ketone but the protonated form of this enamine could not be cyclised to the indole α-position.Both indol-2-yl 1-methyl-1,2,5,6-tetrahydropyridin-4-yl ketone (1c) and its isomer (1d) were cyclised to 5-membered ketones by mineral acid catalysed Michael-type addition of indole β- and α-positions respectively onto the unsaturated ketone systems.Ketone (1d) was transformed to 1-acetylindol-3-yl 3-acetyl-1,4,5,6-tetrahydropyridin-4-yl ketone by hot acetic anhydride.Strong base treatment of indol-3-yl(1,2,5,6-tetrahydropyridin-4-yl) methane caused isomeration of the double bond into conjugation with the indole rather than into the endocyclic enamine position.