title: Nickel-Catalyzed Facile [2+2+2] Cyclotrimerization of Unactivated Internal Alkynes to Polysubstituted Benzenes.
abstract: A catalytic [2+2+2] cyclotrimerization of unactivated internal alkynes providing cyclotrimerization products in excellent yields with high regioselectivity is described. The transformation is accomplished by using a simple catalytic mixture comprising Ni(acac)2, an imidazolium salt and a Grignard reagent at room temperature or 60 °C for 20 min or 1 h.
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.
authors.forename: Fei
authors.initials: F
authors.lastname: Xue
authors.affiliation: Institute of Materials Research and Engineering, Agency for Science, Technology and Research, 2 Fusionopolis Way, Innovis, Singapore, 138634, Singapore.
authors.forename: Ying Kai
authors.initials: YK
authors.lastname: Loh
authors.affiliation: Institute of Materials Research and Engineering, Agency for Science, Technology and Research, 2 Fusionopolis Way, Innovis, Singapore, 138634, Singapore.
authors.forename: Xiaolu
authors.initials: X
authors.lastname: Song
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.
authors.forename: Wei Jie
authors.initials: WJ
authors.lastname: Teo
authors.affiliation: Institute of Materials Research and Engineering, Agency for Science, Technology and Research, 2 Fusionopolis Way, Innovis, Singapore, 138634, Singapore.|School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore, 637459, Singapore.
authors.forename: J Y Darrence
authors.initials: JY
authors.lastname: Chua
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.|Institute of Materials Research and Engineering, Agency for Science, Technology and Research, 2 Fusionopolis Way, Innovis, Singapore, 138634, Singapore.
authors.forename: Jin
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.|Institute of Materials Research and Engineering, Agency for Science, Technology and Research, 2 Fusionopolis Way, Innovis, Singapore, 138634, Singapore.|Department of Chemistry, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.
authors.forename: T S Andy
authors.initials: TS
authors.lastname: Hor
keywords: Grignard reagents; N-heterocyclic carbenes (NHCs); alkynes; catalytic [2+2+2] cyclotrimerization; nickel