Two DistinctDiazo–Diazo Cross-Coupling Reactionsbetween α‑Aryldiazo Ketones and Vinyldiazo Esters UsingGold Catalyst and Tetrabutylammonium Fluoride

Two distinct coupling reactions of α-aryldiazo ketones with vinyldiazo esters are described using gold catalyst (5 mol %) and Bu₄NF promoter (1.5 equiv), respectively. This new synthetic scheme involves a prior rearrangement of α-aryldiazo ketones to generate diarylketenes under thermal conditions whereas vinyldiazo esters serve as nucleophiles to afford isolable 4-siloxy-1-diazo-pent-4-en-2-ones. This diazo–diazo cross-coupling reaction yields highly substituted cyclopentenones using gold catalyst and substituted pyrazole derivatives with Bu₄NF promoter.