Heterocyclen-Synthesen mit Monothiomalonsäure-Amiden: Synthese von 3-Oxo-2,3-dihydroisothiazolo [5,4-b] pyridinen und 3-Oxo-2,3-dihydroisothiazolo[5,4-d]pyrimidinen

Abstract

Heterocyclic Syntheses with Monothiomalonic Amides: Synthesis of 3-Oxo-2,3-dihydroisothiazolo[5,4-b]pyridines and 3-Oxo-2,3-dihydroisothiazolo[5,4-d]pyrimidines The monothiomalonic acid amides 5, prepared from cyanoacetamides 4 and hydrogen sulphide, react with diketones 6 or aldehyde derivatives 7 to give the 2-thioxo-1,2-dihydropyridine-3-carboxamides 8 which can be cyclised to the 3-oxo-2,3-dihydroisothiazolo[5,4-d]pyridines 2. Amides 5 also react with s-triazine to give the 3-oxo-2,3-dihydroisothiazolo [5,4-d]pyrimidines 3.