title: Rhodium-catalyzed arylative and alkenylative cyclization of 1,5-enynes induced by geminal carbometalation of alkynes.
abstract: A rhodium(I)-catalyzed addition-cyclization of 1,5-enynes with aryl- and alkenylboronic acids has been developed. The reaction allows for efficient C-C coupling of multiple reactive components while accomplishing a net R,H-addition in a single step under mild conditions. In the presence of [Rh(OH)(COD)]2 catalyst and triethylamine base in methanol solvent, a range of 1,5-enynes undergo an intermolecular addition with a wide variety of aryl- and alkenylboronic acids and concomitant endo-selective cyclization to yield 1-aryl and alkenyl-substituted cyclopentene derivatives as the products. Deuterium labeling studies suggest that the reaction involves formation of a rhodium vinylidene complex with the terminal alkyne of the enyne substrate. The subsequent migration of the aryl or alkenyl group from the rhodium center to the alpha-carbon of the vinylidene ligand gives a vinyl rhodium complex, a formal 1,1-carbometalation process of the alkyne. This vinyl rhodium then adds to the pendent alkene, and the protodemetalation of the resulting rhodium enolate affords the product.
authors.affiliation: Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: Yiyun
authors.initials: Y
authors.lastname: Chen
authors.forename: Chulbom
authors.initials: C
authors.lastname: Lee
mesh_terms: D000466:Alkadienes / Q000138:chemical synthesis*; D000480:Alkynes / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D006841:Hydrocarbons, Aromatic / Q000737:chemistry*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000466:Alkadienes; D000480:Alkynes; D006841:Hydrocarbons, Aromatic; D009942:Organometallic Compounds; D012238:Rhodium