- Isothiourea-catalyzed enantioselective α-alkylation of esters via 1,6-conjugate addition to para-quinone methides
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The isothiourea-catalyzed enantioselective 1,6-conjugate addition of para-nitrophenyl esters to 2,6-disubstituted para-quinone methides is reported. para-Nitrophenoxide, generated in situ from initial N-acylation of the isothiourea by the para-nitrophenyl ester, is proposed to facilitate catalyst turnover in this transformation. A range of para-nitrophenyl ester products can be isolated, or derivatized in situ by addition of benzylamine to give amides at up to 99% yield. Although low diastereocontrol is observed, the diastereoisomeric ester products are separable and formed with high enantiocontrol (up to 94:6 er).
- Arokianathar, Jude N.,Greenhalgh, Mark D.,Hartley, Will C.,McLaughlin, Calum,Ng, Sean,Slawin, Alexandra M. Z.,Smith, Andrew D.,Stead, Darren
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supporting information
(2021/11/01)
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- TBAB-catalyzed 1,6-conjugate sulfonylation of paraquinone methides: A highly efficient approach to unsymmetrical gem-diarylmethyl sulfones in water ?
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A highly efficient sulfonylation of para-quinone methides with sulfonyl hydrazines in water has been developed on the basis of the mode involving a tetrabutyl ammonium bromide (TBAB)-promoted sulfa-1,6-conjugated addition pathway. This reaction provides a green and sustainable method to synthesize various unsymmetrical diarylmethyl sulfones, showing good functional group tolerance, scalability, and regioselectivity. Further transformation of the resulting diarylmethyl sulfones provides an efficient route to some functionalized molecules.
- Liu, Zhang-Qin,You, Peng-Sheng,Zhang, Liang-Dong,Liu, Da-Qing,Liu, Sheng-Shu,Guan, Xiao-Yu
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supporting information
(2020/02/11)
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- Organocatalyzed asymmetric 1,6-conjugate addition of para-quinone methides with dicyanoolefins
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A chiral thiourea catalyzed asymmetric 1,6-conjugate addition of para-quinone methides with dicyanoolefins has been developed. The reaction provided an efficient approach to the synthesis of chiral diarylmethine skeletons in good yields (up to 99% yield) with high diastereo- and enantioselectivity (>20:1 dr and up to 99.5:0.5 er), also on a gram scale. The preliminary mechanistic study showed that the remote stereocontrol was achieved through intermolecular hydrogen-bond interaction between the chiral thiourea catalyst and the para-quinone methides directly for the first time.
- Li, Xuanyi,Xu, Xiuyan,Wei, Weiwei,Lin, Aijun,Yao, Hequan
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supporting information
p. 428 - 431
(2016/02/19)
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- 1,6-Addition Arylation of para-Quinone Methides: An Approach to Unsymmetrical Triarylmethanes
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A 1,6-addition arylation reaction of para-quinone methides with α-isocyanoacetamides and electron-rich aromatic compounds under metal-free conditions has been developed. BF3·Et2O plays two roles in the reaction: catalyzing the cyclization of α-isocyanoacetamides to give oxazoles, and activating the para-quinone methides to achieve the 1,6-addition arylation process. The reaction shows good functional group tolerance, scalability, and regioselectivity. It is a consice protocol for the synthesis of diverse unsymmetrical triarylmethanes. Further transformation of the resulting triarylmethanes provides an efficient route to some functionalized molecules.
- Gao, Shang,Xu, Xiuyan,Yuan, Zhenbo,Zhou, Haipin,Yao, Hequan,Lin, Aijun
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supporting information
p. 3006 - 3012
(2016/07/11)
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- Synthesis of spiro[2.5]octa-4,7-dien-6-one with consecutive quaternary centers via 1,6-conjugate addition induced dearomatization of para-quinone methides
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An efficient one-pot approach for the synthesis of spiro[2.5]octa-4,7-dien-6-ones by employing para-quinone methides has been developed. The reaction proceeded smoothly in high yields under mild conditions without the use of metals. Moreover, all products obtained herein contained two or three consecutive quaternary centers.
- Gai, Kuo,Fang, Xinxin,Li, Xuanyi,Xu, Jinyi,Wu, Xiaoming,Lin, Aijun,Yao, Hequan
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supporting information
p. 15831 - 15834
(2015/11/10)
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- Quinone alkide synthesis system
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A novel and efficient oxidation process for preparing quinone alkides from the corresponding tri-alkyl or phenyl hindered phenols, utilizing ferricyanide as the secondary oxidant in combination with persulfate as the primary oxidant.
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