- Catalytic asymmetric [2+2] cycloaddition between quinones and fulvenes and a subsequent stereoselective isomerization to 2,3-dihydrobenzofurans
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The catalytic enantioselective [2+2] cycloaddition between quinones and fulvenes was achieved, for the first time, by the use of a chiral copper(ii) complex catalyst. The transformation afforded a series of enantiomerically enriched [6,4,5]-tricyclic cyclobutane derivatives in good yields with excellent regio- and stereoselectivities. Furthermore, the [2+2] adducts could be easily converted into formal [3+2] adducts efficiently and stereoselectively.
- Zheng, Haifeng,Xu, Chaoran,Wang, Yan,Kang, Tengfei,Liu, Xiaohua,Lin, Lili,Feng, Xiaoming
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supporting information
p. 6585 - 6588
(2017/07/10)
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- Chiral cobalt(II) complex catalyzed Friedel-Crafts aromatization for the synthesis of axially chiral biaryldiols
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An efficient atroposelective synthesis of axially chiral biaryldiols via asymmetric Friedel-Crafts aromatization between p-quinones and 2-naphthols was developed. A chiral cobalt(ii) complex of N,N′-dioxide enabled the process to generate axially chiral biaryldiols in up to 98% yield and 95% ee. A large range of substituents at different positions of p-quinones and 2-naphthols was tolerable. The configuration of the product and the chiral N,N′-dioxide-Co(ClO4)2 catalyst was identified by X-ray crystal diffraction analysis and a possible catalytic model was suggested.
- Xu, Chaoran,Zheng, Haifeng,Hu, Bowen,Liu, Xiaohua,Lin, Lili,Feng, Xiaoming
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supporting information
p. 9741 - 9744
(2017/09/07)
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- Substituent effects in the oxidation of 2-alkyl-1,4-dialkoxybenzenes with ceric ammonium nitrate
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Increased steric size of alkyl groups and the presence of coordinating atoms on alkoxy groups have both been found to contribute to decreasing yields of diquinones upon reaction of 2-alkyl-1,4-dialkoxybenzenes with CAN. The overall hydrophilicity of the substrates does not appear to be a significant factor in determining the diquinone yield for these reactions.
- Love, Brian E.,Simmons, Alexander L.
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p. 5712 - 5715
(2016/11/29)
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- Effects of reaction conditions on quinone/diquinone product ratios in the oxidation of 1,4-dimethoxybenzene derivatives with ceric ammonium nitrate
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Proper choice of reaction conditions allows formation of either the quinone or corresponding diquinone as the major product upon treatment of 2-alkyl-1,4-dimethoxybenzenes with ceric ammonium nitrate.
- Love, Brian E.,Duffy, Brian C.,Simmons, Alexander L.
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supporting information
p. 1994 - 1997
(2014/04/03)
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