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Rhodium-NHC-Catalyzed gem-Specific O-Selective Hydropyridonation of Terminal Alkynes
María Galiana-Cameo1, Raúl Romeo1, Asier Urriolabeitia2
1Departamento de Química Inorgánica-Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), Universidad de Zaragoza-CSIC, C/Pedro Cerbuna 12, CP, 50009, Zaragoza, Spain.
Abstract:
The dinuclear complex [Rh(μ-Cl)(η2 -coe)(IPr)]2 is an efficient catalyst for the O-selective Markovnikov-type addition of 2-pyridones to terminal alkynes. DFT calculations support a hydride-free pathway entailing intramolecular oxidative protonation of a π-alkyne by a κ1 N-hydroxypyridine ligand. Subsequent O-nucleophilic attack on a metallacyclopropene species affords an O-alkenyl-2-oxypyridine chelate rhodium intermediate as the catalyst resting state. The release of the alkenyl ether is calculated as the rate-determining step.
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