Consecutive 3CR synthesis of heterocycles by Cu-catalyzed alkyne carboxylation

What is it about?

A copper(I)-catalyzed carboxylation of terminal alkynes followed trapping of the carboxylate with methyl iodide provides a straightforward access to 3-substituted methyl propiolates that can be reacted in the same reaction vessel in a consecutive fashion to give 2,6-disubstituted pyrimid-4(3H)-ones and 1,5-disubstituted 3-hydroxypyrazoles in moderate to good yields.

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Why is it important?

The Cu(I)-catalyzed carboxylation with carbon dioxide as C1 source therefore provides an environmentally benign entry to three-carbon building blocks in heterocyclic synthesis.