Synhtesis of 2H-Thiopyrans by rhodium(II) acetate-catalyzed reaction of 4-amino-2,5-dihydro-3-thiophenecarbonitriles with#alpha#-diazocarbonyl compounds II[1]

摘要

The reaction of 4-amino-2,5-dihydro-2-methyl-3-thiophenecarbonitriles with #alpha#-diazocarbonyl compounds in thepresence of rhodium(II) acetate gave regioselectively 4-cyano-2H-thiopyrans(C_2-S insertion) in moderate to good yields;5-cyano-2H-thiopyrans(C_5-S insertion) were not isolated.The starting compounds were synthesized by reaction of tetrahydro-2-and -5-methyl-4-oxo-3-thiophenecarbonitriles with morpholine,piperidine,and pyrrolidine in the presence of formic acid in ethanol.