Efficient Synthesis of alpha -Ketoamides via 2-Acyl-5-aminooxazoles by Reacting Acyl Chlorides and alpha -Isocyanoacetamides

Acyl chlorides R1COCl [R1 = Et, n-pentyl, PhCH2CH2, 2-cyclopentylethyl, (S)-PhCHEt] efficiently reacted with alpha -isocyanoacetamides R2R3NCOCH(NC)R4 (R2 = H, R3 = n-Bu, PhCH2, HC==CCH2; R2 = Me, R3 = HC==CCH2, PhCH2; R2R3N = 4-morpholinyl; R4 = H, Me, PhCH2) in dichloromethane in the presence of triethylamine to give 2-acyl-5-aminooxazoles I. Subsequent acid hydrolysis of the 5-aminooxazole moiety leads to alpha -ketoamides II in good overall yields. [on SciFinder (R)]