- Enantioselective Palladium(II)-Catalyzed Intramolecular Aminoarylation of Alkenes by Dual N?H and Aryl C?H Bond Cleavage
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An asymmetric palladium-catalyzed intramolecular oxidative aminoarylation of alkenes has been developed with quinoline–oxazoline chiral ligands and Ag2CO3 as the oxidant. Various indolines containing a quaternary stereogenic center were synthesized in high yield with excellent enantioselectivity. Preliminary mechanistic studies suggest that the addition of a catalytic amount of phenylglyoxylic acid significantly accelerates the reaction and slightly enhances the enantioselectivity.
- Zhang, Wen,Chen, Pinhong,Liu, Guosheng
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supporting information
p. 5336 - 5340
(2017/04/27)
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- Novel One-Pot Synthetic Method for Propargyl Alcohol Derivatives from Allyl Alcohol Derivatives
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An efficient one-pot procedure for the synthesis of propargyl alcohol derivatives from allyl alcohol derivatives has been developed. The key to this transformation from a C-C double bond to a C-C triple bond is that hydrogen bromide elimination from 1,2-dibromoalkanes that contain a neighboring oxygen functional group is promoted by the inductive electron-withdrawing effect of the oxygen functional group. In the one-pot reaction, tetrabutylammonium hydroxide was the best base, and the addition of molecular sieves 13X also promoted the reaction.
- Kutsumura, Noriki,Inagaki, Mai,Kiriseko, Akito,Saito, Takao
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p. 1844 - 1850
(2015/06/30)
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- Metal-free regioselective hydrobromination of alkynes through CH/CBr activation
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A metal-free regioselective hydrobromination of alkynes has been developed to provide the Markovnikov-type vinyl bromides in good yields using dibromomethane/N,N-dimethylaniline as in-situ 'HBr' source. This protocol also represents an elegant example of the activation of sp2 CH and CBr bonds in one pot, in which 'HBr' is generated and transferred under mild metal-free conditions. D-incorporated experiments were employed to investigate the reaction mechanism and a plausible reaction path was proposed.
- Chen, Xiuling,Chen, Tieqiao,Xiang, Yuqiang,Zhou, Yongbo,Han, Daoqing,Han, Li-Biao,Yin, Shuang-Feng
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supporting information
p. 4572 - 4575
(2014/12/10)
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- 1,8-diazabicyclo[5.4.0]undec-7-ene-promoted regioselective elimination of vicinal dibromides having an adjacent O-and/or N-functional group
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We have investigated the DBU-promoted HBr-elimination of vicinal dibromides having an adjacent O- and/or N-functional group under mild basic conditions. The elimination of 1-oxygenfunctionalized 2,3-dibromopropanes was more regioselective than that of 1-n
- Kutsumura, Noriki,Iijima, Masatoshi,Toguchi, Shohei,Saito, Takao
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supporting information; experimental part
p. 1231 - 1232
(2011/11/30)
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- Efficient synthesis of functionalized furans via ruthenium-catalyzed cyclization of epoxyalkyne derivatives
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Ruthenium catalyst TpRuPPh3(CH3CN)2Cl is found to effect the cyclization of epoxyalkynes to furans in the presence of Et3N. The reactions worked well for various epoxyalkynes with suitable oxygen and nitrogen functionalities with low loading of catalyst. It failed with disubstituted epoxyalkynes. The mechanism was elucidated by a deuterium labeling experiment that suggested that the mechanism involved a ruthenium-vinylidenium intermediate.
- Lo, Ching-Yu,Guo, Hongyun,Lian, Jian-Jou,Shen, Fwu-Ming,Liu, Rai-Shung
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p. 3930 - 3932
(2007/10/03)
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- Building Blocks for the Stereocontrolled Synthesis of 1,3-Diols of Various Configurations
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A Sharpless epoxidation of the pentadienol 12 afforded the unsaturated epoxyalcohol 11 with 97.7% ee. Silylation of 11 and ozonolysis provided the epoxyketone 14. A completely anti-selective reduction of 14 succeeded with Zn(BH4)2. It led to the epoxyalcohol 15 which was converted into the acetonide alcohols 21 and 23, building blocks for enantiopure anti-1,3-diols. Alternatively, the same epoxyketone 14 and cp2Ti(III)Cl / 1,4-cyclohexadiene gave the β-hydroxyketone 16. This compound was transformed into the acetonide alcohols 22 and 24, building blocks for enantiopure syn-1,3-diols.
- Weigand, Stefan,Brückner, Reinhard
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p. 225 - 228
(2007/10/03)
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