title: Rhodium-catalyzed intra- and intermolecular [5 + 2] cycloaddition of 3-acyloxy-1,4-enyne and alkyne with concomitant 1,2-acyloxy migration.
abstract: A new type of rhodium-catalyzed [5 + 2] cycloaddition was developed for the synthesis of seven-membered rings with diverse functionalities. The ring formation was accompanied by a 1,2-acyloxy migration event. The five- and two-carbon components of the cycloaddition are 3-acyloxy-1,4-enynes (ACEs) and alkynes, respectively. Cationic rhodium(I) catalysts worked most efficiently for the intramolecular cycloaddition, while only neutral rhodium(I) complexes could facilitate the intermolecular reaction. In both cases, electron-poor phosphite or phosphine ligands often improved the efficiency of the cycloadditions. The scope of ACEs and alkynes was investigated in both the intra- and intermolecular reactions. The resulting seven-membered-ring products have three double bonds that could be selectively functionalized.
authors.affiliation: School of Pharmacy, University of Wisconsin, Madison, Wisconsin 53705, United States.
authors.forename: Xing-Zhong
authors.initials: XZ
authors.lastname: Shu
authors.forename: Xiaoxun
authors.initials: X
authors.lastname: Li
authors.forename: Dongxu
authors.initials: D
authors.lastname: Shu
authors.forename: Suyu
authors.initials: S
authors.lastname: Huang
authors.forename: Casi M
authors.initials: CM
authors.lastname: Schienebeck
authors.forename: Xin
authors.initials: X
authors.lastname: Zhou
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Robichaux
authors.forename: Weiping
authors.initials: W
authors.lastname: Tang
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D003516:Cycloparaffins / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D012238:Rhodium / Q000737:chemistry*
chemical_list: D000480:Alkynes; D003516:Cycloparaffins; D012238:Rhodium