- Selective monochlorination of unsymmetrical vicinal diols with chlorinated iminium chlorides
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Chlorinated iminium chlorides have been identified to promote the highly efficient and selective mono-chlorination of unsymmetrical vicinal diols. Vilsmeier reagent, namely, (chloromethylene)dimethyliminium chloride, enables highly reactive and regioselective chlorination of 1,2- and 1,3-diols featured one secondary benzylic hydroxy group and one primary aliphatic hydroxy group to give the corresponding 1,2- and 1,3-chlorohydrins. Viehe's salts (α,α-dichloro iminium salts) exhibit excellent reactivity and good selectivity for vicinal diols to give the corresponding chlorohydrin carbamates via a cyclic intermediate in situ. The chlorination protocols tolerate diverse functional groups, including halogens, naphthalene rings, nitro, and cyano. Moreover, the optical purity of chiral diols could be retained during this chlorination reaction.
- Li, Chengyang,Li, Xiaotong,Wang, Yu,Wu, Xiaoyu,Xie, Xiaomin,Yang, Liqun,Zhang, Zhaoguo
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- Synthesis of 3-arylcoumarins through N-heterocyclic carbene catalyzed condensation and annulation of 2-chloro-2-arylacetaldehydes with salicylaldehydes
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The condensation reaction of 2-chloro-2-arylacetaldehyde with salicylaldehyde catalyzed by N-heterocyclic carbene (NHC) leading to 3-arylcoumarin was studied. A number of 3-arylcoumarin derivatives were obtained in good to excellent yields via this umpolung reaction. This reaction is facile and experimentally simple and mild.
- Jiang, Yuansong,Chen, Wanzhi,Lu, Weimin
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p. 3669 - 3676
(2013/05/08)
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- Facile and regioselective conversion of epoxides into β-chlorohydrins using ZrCl4
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Epoxides were efficiently converted into the corresponding β-chlorohydrins in good yields by treatment with ZrCl4 in acetonitrile.
- Smitha,Reddy, Ch. Sanjeeva
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p. 300 - 301
(2007/10/03)
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