- Palladium-Catalyzed Ortho-Alkoxylation of N-Benzoyl α-Amino Acid Derivatives at Room Temperature
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An efficient palladium-catalyzed ortho-alkoxylation of N-benzoyl α-amino acid derivatives at room temperature has been explored. This novel transformation, using amino acids as directing groups, Pd(OAc)2 as catalyst, alcohols as the alkoxylation reagents, and PhI(OAc)2 as the oxidant, showed wide generality, good functional tolerance, and high monoselectivity and regioselectivity.
- Li, Shuangjie,Zhu, Wei,Gao, Feng,Li, Chunpu,Wang, Jiang,Liu, Hong
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p. 126 - 134
(2017/04/26)
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- Structural and mechanistic studies of the copper(II)-assisted ortho-hydroxylation of benzoates by trimethylamine N-oxide
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N-benzoyl-2-methylalanine (H2L1) is ortho-hydroxylated stereoselectively by trimethylamine N-oxide (TMAO) in the presence of copper(II). The experimental structure of [Cu(L1)(TMAO)2] suggests that the oxygen transfer agent TMAO transfers the oxygen atom to copper(II), and (L1)2-, coordinated to copper(II) by a carboxylate oxygen and the amide nitrogen donor, is well pre-organized for an oxygen transfer from copper to the ortho carbon atom of the benzene ring. Product analyses as a function of reaction time of the copper(II)-mediated ortho-hydroxylation reaction with H2L1 and various derivatives support the suggestion of a reactive copper-oxo or copper-hydroxo intermediate, stabilized by a five-membered chelate with hard carboxylate and N-amide donors. The analysis also suggests that there is a pre-equilibrium with a Cu:L=1:1 ratio, and this might involve Cu/L2-/TMAO or dicopper complexes. Depending on the ligand H2L, complexation with the salicylate product may inhibit the ortho-hydroxylation reaction.
- Buijs, Wim,Comba, Peter,Corneli, Danny,Pritzkow, Hans
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