FEATURES OF THE REACTION OF 5-AMINOISOXAZOLES WITH DIETHYL 2-OXOSUCCINATE. SYNTHESIS OF ETHYL 6-HYDROXYISOXAZOLO[5,4-b]PYRIDINE-4-CARBOXYLATES

Abstract

Condensation of 5-aminoisoxazoles bearing substituents at position 3 with diethyl 2-oxosuccinate sodium salt in trifluoroacetic acid proceeded with the formation of diethyl (Z)-2-(5-amino-3-methylisoxazol-4-yl)but-2-enedioates. Cyclization of the latter in the presence of sodium ethoxide in alcohol provided ethyl 6-hydroxyisoxazolo[5,4-b]pyridine-4-carboxylates. Ester hydrolysis gave the respective 6-hydroxyisoxazolo[5,4-b]pyridine-4-carboxylic acids.

Authors: Valery S. Tolkunov*, Andrew S. Tolkunov, Olga V. Smirnova, Sergei V. Tolkunov