Thermal Cyclization of Ketene Dithioacetals: A Convenient Synthetic Route to Substituted 2(1<i>H</i>)-Quinolinones and 2(1<i>H</i>)-Pyridones
作者:Chwang Siek Pak、Eun Bok Choi
DOI:10.1055/s-1992-26361
日期:——
Acyl(arylcarbamoyl)ketene dithioacetals 2 and acyl(1-alkenylcarbamoyl)ketene dithioacetals 5 obtained from the corresponding ß-oxo amides 1, 4 were thermally cyclized to give various 3-acyl-4-alkylthio-2(1H)-quinolinones 3, and 3-acyl-4-alkylthio-5-aryl-2(1H)-pyridones 6, respectively, depending on the substituent of the amide group.
A facile and efficient synthesis of substituted pyridine-2,6(1H,3H)-diones via an intramolecular [5 + 1] annulation of readily available α-alkenoyl-α-carbamoyl ketene-S,S-acetals mediated by phosphorus bromide (PBr3) under very mild conditions is described.
A facile and efficient synthesis of fully substituted pyridin-2(1H)-ones has been developed by the reaction of readily available alpha-oxoketene-S,S-acetals with malononitrile in the presence of sodium methoxide in methanol under reflux. (C) 2011 Elsevier Ltd. All rights reserved.