Photolysis of 1,1,1-Triphenyl-2-alkenes and Methyl Triphenylacetate
作者:Min Shi、Yoshiki Okamoto、Setsuo Takamuku
DOI:10.1246/cl.1990.1079
日期:1990.7
in methanol 1,1,1-triphenyl-2-alkene or methyl triphenylacetate underwent two kinds of α,α-elimination of two phenyl groups and phenyl-alkenyl groups or phenyl-methoxycarbonyl groups to give biphenyl, 1-phenylalkene or methyl benzoate, and two kinds of corresponding carbene intermediates, which inserted into the O–H bond of methanol to afford two kinds of methyl ethers, respectively.
Isolation and X-ray Crystal Structure of an Unusual Biscarbene Metal Complex and Its Reactivity toward Cyclopropanation and Allylic C−H Insertion of Unfunctionalized Alkenes
作者:Yan Li、Jie-Sheng Huang、Zhong-Yuan Zhou、Chi-Ming Che
DOI:10.1021/ja003184q
日期:2001.5.1
Shi, Min; Shouki, Kouji; Okamoto, Yoshiki, Journal of the Chemical Society. Perkin transactions I, 1990, # 9, p. 2443 - 2450
Discrete Bridging and Terminal Copper Carbenes in Copper-Catalyzed Cyclopropanation
作者:Xuliang Dai、Timothy H. Warren
DOI:10.1021/ja047935q
日期:2004.8.1
The Cu(I) beta-diketiminate [Me2NN]Cu(eta(2)-ethylene) (2) catalyzes the cyclopropanation of styrene with N2CPh2 to give 1,1,2-triphenylcyclopropane in 67% yield. Addition of N2CPh2 to 2 equiv of 2 allows for the isolation of the dicopper carbene [Me2NN]Cu}(2)(mu-CPh2) (3) in which the diphenylcarbene moiety is symmetrically bound between two [Me2NN]Cu fragments (Cu-C = 1.922(4) and 1.930(4) Angstrom) with a Cu-Cu separation of 2.4635(7) Angstrom. In toluene-d(8) solution, 3 reversibly dissociates a [Me2NN]Cu fragment to give [Me2NN]Cu(toluene) and the terminal carbene [Me2NN]Cu=CPh2. Dicopper carbene 3 reacts with 3 equiv of styrene to give 1,1,2-triphenylcyclopropane and 2 equiv of [Me2NN]Cu(eta(2)-styrene) within minutes. DFT studies with simplified ligands indicate a stronger Cu-C pi-back-bonding interaction from two Cu(I) centers to the carbene acceptor orbital in a dicopper carbene than that present in a monocopper carbene. Nonetheless, the terminal carbene [Me3NN]Cu=CPh2 (8) that possesses a p-methyl group on each beta-diketiminato N-aryl ring may be isolated and exhibits a shortened Cu-C distance of 1.834(3) Angstrom. The stoichiometric cyclopropanation of styrene by 8 in 1,4-dioxane is first-order in both copper carbene 8 and styrene with activation parameters DeltaH(not similar or equal to) = 10.4(3) kcal/mol and DeltaS(not similar or equal to) = -32.3(9) cal/mol-K. In 1,4-dioxane, 8 decomposes to Ph2C=CPh2 via first-order kinetics with activation parameters DeltaH(not similar or equal to) = 21(1) kcal/mol and DeltaS(not similar or equal to) = -8(3) cal/mol-K. Arene solutions of thermally sensitive terminal carbene 8 decompose to [Me3NN]-Cu(arene), which reacts with 8 still present in solution to give the more thermally stable [Me3NN]Cu}(2)-(mu-CPh2).
SHI, MIN;SHOUKI, KOUJI;OKAMOTO, YOSHIKI;TAKAMUKU, SETSUO, J. CHEM. SOC. PERKIN TRANS. PT 1,(1990) N, C. 2443-2450