One-pot synthesis of N-heterocyclic compounds from cyclopropenethione derivatives

The one-pot reaction of 2-tert-butylthio-3-phenylcyclopropenethione (1a) an d its 3-(2-thienyl) derivative (1b) with lithium pyrrolidinide at -70 degre es C, followed by methylation with methyl iodide, gives 6-methylthio-5-phen yl-2,3-dihydro-1H-pyrrolizine (2a) and its 5-(2-thienyl) derivative (2b), r espectively. The reaction of 2-tert-butylthio-3-(pyrrolidin-1-yl)cycloprope nethione (1c) with phenyllithium gives also 2a in a high yield under simila r conditions, and the reactions of la with N-lithium salts of 3-pyrroline, hexamethyleneimine, indoline, and carbazole, piperidine-potassium tert-buto xide mixture, and phenyllithium give 6-methylthio-5-phenyl-3H-pyrrolizine ( 3), 2-methylthio-3-phenyl-6,7,8,9-tetrahydro-5H-pyrrolo[1,2a]azepine (5), 6 -tert-butylthio-5-methylthio-4-phenyl-1,2-dihydro-6H-pyrrolo[3,2,1-ij]quino line (8), 4-tert-butylthio-5-methylthio-6-phenyl-4H-pyrido[3,2, 1-jk]carbaz ole (7), 2-methylthio-3-phenyl-5,6,7,8-tetrahydroindolizine (4), and 1-tert -butylthio-2-methylthio-3-phenylindene (9), respectively. The structures of 2a and 3 were determined by X-ray analyses of their tricarbonylchromium co mplexes.