Rhodium‐NHC‐Catalyzed gem‐Specific O‐Selective Hydropyridonation of Terminal Alkynes. (19th March 2022)

• Record Type: Journal Article
• Authors: Galiana‐Cameo, María; Romeo, Raúl; Urriolabeitia, Asier; Passarelli, Vincenzo; Pérez‐Torrente, Jesús J.; Polo, Victor; Castarlenas, Ricardo
• Is Part Of: Angewandte Chemie. Volume 134:Number 20(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-03-19
• Subjects: Alkenylation -- Alkyne Hydrofunctionalization -- C−O Coupling -- N-Heterocyclic Carbene -- Pyridone; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.202117006
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: The dinuclear complex [Rh(μ‐Cl)(η 2 ‐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 κ 1 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. Abstract : A Rh‐IPr catalyst was reported for the synthesis of gem ‐ O ‐alkenyl‐oxypyridines by selective O ‐addition of 2‐pyridones to terminal alkynes. A preferable N ‐coordination mode within the metallacyclopropene intermediate species causes a seesaw effect responsible for the O ‐nucleophilic attack.