Ivo C. Ivanov

A Convenient Approach to the Synthesis of Dialkyl 5‐Oxo‐1,2‐dihydro‐5H‐chromeno [4,3‐b]pyridine‐2,3‐dicarboxylates

Abstract Coumarin and its analogs are considered privileged scaffolds in the current synthetic and pharmacological research. The chemical behavior of enaminocarbaldehydes of the coumarin moiety under intramolecular Wittig reaction conditions in the presence of triphenylphosphine and dimethyl or diethyl acetylenedicarboxylates has been studied, resulting in the isolation of a series of dimethyl and diethyl 5‐oxo‐1,2‐dihydro‐5H‐chromeno[4,3‐b]pyridine‐2,3‐dicarboxylates in good to high yields.

Addition of Some Enamino Esters to 3-Substituted Coumarins

Abstract The addition of the enamino esters 1a, b to several coumarins with electron-withdrawing 3-substituents 2 yielded 3 and 4, whereas ethyl 3-amino-2-butenoate (1c) reacted surprisingly with its C-4 to give either an adduct 8 or pyrido [3,4-c] chromene 9.

Synthesis of Some Substituted 2H-Pyrano[3,2-c]pyridine-2,5(6H)-diones. Reaction of Their 3-Acetyl Derivatives with Methyl 3-Amino-2-butenoate

Abstract Formylation of 4-hydroxy-6-methyl-2(1H)-pyridones and subsequent cyclization with a Wittig reagent or with CH-acidic esters gave a series of title compounds. The same starting pyridones reacted with methyl 3-amino-2-butenoate directly to the corresponding 4,7-dimethylpyrano[3,2-c]pyridines.