Record number :
Title of article :
Structural and mechanistic studies of the copper(II)-assisted ortho-hydroxylation of benzoates by trimethylamine N-oxide
Author/Authors :
Wim Buijs، نويسنده , , Peter Comba، نويسنده , , Danny Corneli، نويسنده , , Hans Pritzkow، نويسنده ,
Issue Information :
دوفصلنامه با شماره پیاپی سال 2002
Pages :
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Abstract :
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.
Keywords :
ortho-Hydroxylation , Salicylic acid , Selectivity , Reaction mechanism , Chelate ring size
Journal title :
Journal of Organometallic Chemistry
Link To Document :