title: An efficient, overall [4+1] cycloaddition of 1,3-dienes and nitrene precursors.
abstract: Intermolecular cycloadditions of conjugated dienes and nitrene precursors usually produce aziridines. A generally useful method was lacking to directly provide the [4+1] cycloadducts, 3-pyrrolines. We have realized this transformation by using an uniquely active catalyst, copper(II) 1,1,1,5,5,5-hexafluoroacetylacetonate ([Cu(hfacac)(2)]). The method is applicable to a wide array of dienes with good yields. When 1,4-disubstituted dienes are used as substrates, good-to-excellent cis or trans selectivity can be obtained. Interestingly, the cis or trans preference depends on the nature of the substituents, rather than diene geometry. Mechanistic studies reveal that the [4+1] cycloaddition proceeds through diene aziridination and subsequent ring expansion. Among common copper catalysts, only [Cu(hfacac)(2)] can efficiently catalyze both steps, which explains the unique efficiency of the catalyst.
authors: Department of Medicinal Natural Products, West China School of Pharmacy, Sichuan University, Chengdu, 610041, P. R. China.
authors: Qiong
authors: Q
authors: Wu
authors: Jian
authors: J
authors: Hu
authors: Xinfeng
authors: X
authors: Ren
authors: Jianrong
authors: J
authors: Zhou
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D001388:Aziridines / Q000737:chemistry*; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D003500:Cyclization; D007097:Imines / Q000737:chemistry*; D007700:Kinetics; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000475:Alkenes; D001388:Aziridines; D007097:Imines; D009942:Organometallic Compounds; C562216:copper(II) 1,1,1,5,5,5-hexafluoroacetylacetonate; C017621:phenylnitrene; D003300:Copper