Oxidative nucleophilic substitution of hydrogen versus ring-opening in the reaction of 4-r-2-nitrothiophenes with amines. The crucial effect of 4-alkyl groups
4-Alkyl-2-nitrothiophenes [10: R= CH3, CH (OH) CH3, CH (OCH3) CH3] react with secondary aliphatic amines, in the presence of AgNO3, to give 3-alkyl-2-amino-5- nitrothiophenes (12) through an oxidative nucleophilic substitution of hydrogen (ONSH) of synthetic interest. This behavior is in striking contrast with that of the parent 2-nitrothiophene (6), which was found to undergo ring-opening in analogous reaction conditions. A ...