Some reactions of 1-methyl-1,2-dihydropyridines with organic azides. Synthesis and reactions of 1,2,5,6-tetrahydropyridylidene-2-cyan(sulfon)amides and piperidylidene-2-cyan(sulfon)amides

Abstract

The regiospecific 1,3-dipolar cycloaddition reaction of 1,2-dihydropyridines 2 with organic azides 3 affords 2,7-diazabicyclo[4.1.0]hept-4-enes 4. Treatment of 4a with neutral aluminum oxide opened the aziridine ring to afford the 1,2,5,6-tetrahydropyridylidene-2-cyanamide 5. Catalytic hydrogenation of 4 and 5 using palladium-on-charcoal and hydrogen yielded the 1-methyl-2-piperidylidenes 6. Oxidation of 1-methyl-1,2,5,6-tetrahydropyridylidene-2-cyanamide (5) with alkaline hydrogen peroxide yielded the oxirane 7 arising from epoxidation of the 3,4-olefenic bond, whereas oxidation of the bicyclic aziridine 4a with m-chloroperbenzoic acid resulted in epoxidation of the 4,5-olefenic bond and opening of the aziridine ring to give the oxirane 3-methyl-3-aza-7-oxabicyclo[4.1.0]heptylidene-4-cyanamide (10). Base-catalyzed abstraction of the C-3 proton of 1-methyl-2-piperidylidenes 6 yielded the 3-lithio analogs which, after bromination, were converted to the target compounds 18 upon condensation with 4-[(2-aminoethyl)thiomethyl]-5-methylimidazole.