A catalytic multicomponent protocol to dihydropyridine-3-carboxylate from terminal alkynes, isocyanates, and malonates

Simple pyrazoles as efficient organocatalysts for alkyne–CO2 carboxylation and one-pot construction of heterocycles

“…3-Cyano-6-hydroxy-2-pyridones ( 6 ), which are important building units of various drugs and dyes, have been generally synthesized through the [3 + 2 + 1] Guareschi–Thorpe condensation of ethyl acetoacetate, ethyl cyanoacetate, and ammonia (or amines). 19 As shown in Scheme 3d, the propiolate produced by Me 2 Pz-catalyzed carboxylation readily reacts in situ with cyano activated acetamides to produce 6 with or without N -substitution. This represents a new and CO 2 -consuming approach toward the useful precursors of drugs and dyes.…”