title: Nickel-catalyzed substitution reactions of propargyl halides with organotitanium reagents.
abstract: A simple and mild catalytic coupling reaction of propargyl halides with organotitanium reagents is reported. The reaction of propargyl bromide with organo-titanium reagents mediated by NiCl2 (2 mol%) and PCy3 (4 mol%) in CH2Cl2 afforded coupling product allenes in good to excellent yields (up to 95%) at room temperature. However, NiCl2(PPh3)2 was the best catalyst for substituted propargyl halides to yield allenes or alkynes preferentially. On the basis of the experimental results, a possible catalytic cycle has been proposed.
authors.affiliation: Department of Chemistry, National Chung Hsing University, Taichung 402, Taiwan. hmgau@draagon.nchu.edu.tw.
authors.forename: Qing-Han
authors.initials: QH
authors.lastname: Li
authors.forename: Jung-Wei
authors.initials: JW
authors.lastname: Liao
authors.forename: Yi-Ling
authors.initials: YL
authors.lastname: Huang
authors.forename: Ruei-Tang
authors.initials: RT
authors.lastname: Chiang
authors.forename: Han-Mou
authors.initials: HM
authors.lastname: Gau
mesh_terms: D000475:Alkenes / Q000138:chemical synthesis; D000480:Alkynes / Q000138:chemical synthesis; D002384:Catalysis; D009532:Nickel / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D010293:Pargyline / Q000031:analogs & derivatives* / Q000737:chemistry; D013696:Temperature; D014025:Titanium / Q000737:chemistry*
chemical_list: D000475:Alkenes; D000480:Alkynes; D009942:Organometallic Compounds; D009532:Nickel; D010293:Pargyline; D014025:Titanium; C458239:propargyl bromide