One-pot synthesis of 2,5-dihydropyrroles from terminal alkynes, azides, and propargylic alcohols by relay actions of copper, rhodium, and gold

Relay actions of copper, rhodium, and gold formulate a one-pot multistep pathway, which directly gives 2,5-dihydropyrroles starting from terminal alkynes, sulfonyl azides, and propargylic alcohols. Initially, copper-catalyzed 1,3-dipolar cycloaddition of terminal alkynes with sulfonyl azides affords 1-sulfonyl-1,2,3-triazoles, which then react with propargylic alcohols under the catalysis of rhodium. The resulting alkenyl propargyl ethers subsequently undergo the thermal Claisen rearrangement to give a-allenyl-a-amino ketones. Finally, a gold catalyst prompts 5-endo cyclization to produce 2,5-dihydropyrroles.