A consecutive three-component activation-alkynylation-cyclization reaction of (hetero)aryl glyoxylic acids, oxalyl chloride, arylacetylenes, and hydrazides efficiently forms 1,5-diacyl-5-hydroxypyrazolines in moderate to good yields. The structures were unambiguously corroborated by comprehensive NMR spectroscopy and X-ray structure analyses of selected derivatives.
Keywords: C–C coupling; activation; alkynylation; copper; cyclization; multicomponent reactions.