Preparation and reductive transformations of vinylogous sulfonamides (β-sulfonyl enamines), and application to the synthesis of indolizidines
Condensation between the methiodide salts of 1-alkylpyrrolidine-2-thiones and ethyl [(4-methylphenyl)sulfonyl]acetate or 1-[(4-methylphenyl)sulfonyl]propan-2-one afforded several 2-{[(4-methylphenyl)sulfonyl]methylene}pyrrolidines in good yield. These β-sulfonyl enamines are sufficiently nucleophilic for cyclisation with internal electrophiles to give sulfone-substituted indolizines, potentially useful scaffolds for alkaloid synthesis. The carbon-carbon double bond in vinylogous sulfonamides was reduced stereoselectively either by catalytic hydrogenation or by treatment with sodium borohydride to yield β-sulfonyl amines. The sulfone group in β-acyl-β-sulfonyl enamines could be removed by hydrogenolysis with sodium amalgam in THF-methanol to give enaminones.
Michael, Joseph P.,De Koning, Charles R.,Malefetse, Tshepo J.,Yillah, Ibrahim
p. 3510 - 3517
(2007/10/03)
More Articles about upstream products of 826994-58-5