Functional sulfur-containing compounds14. Study of intramolecular cyclization of 2-organylthio-, 2-organylsulfinyl-, and 2-organylsulfonylnicotinic acid esters and nitriles upon action of a base

The Thorpe-Ziegler intramolecular cyclization of 2-RCH2S-, 2-RCH2S(O)-, and 2-RCH2SO2-substituted nicotinic acid esters and nitriles (R is alkyl, aryl, and 2-thienyl) upon the action of potassium tert-butoxide has been studied. The reaction results in the formation of the corresponding 2-R-substituted 3-aminothieno[2,3-b]pyridines, 3-aminothieno[2,3-b]pyridine 1-oxides, and 3-aminothieno[2,3-b]pyridine 1,1-dioxides with the reaction taking place only in the case if R is aryl or 2-thienyl. Methyl esters of 2-RCH2S-, 2-RCH2S(O)-, and 2-RCH2SO2-substituted nicotinic acids also undergo the intramolecular cyclization of the Dieckmann type to form the corresponding 2-R-substituted 3-hydroxythieno[2,3-b]pyridines, thieno[2,3-b]pyridin-3(2H)-one 1-oxides, and thieno[2,3-b]pyridin-3(2H)-one 1,1-dioxides. Such a reaction takes place for all the R groups except when R = AlkCH2S and AlkCH2S(O).