2,2-二取代的2 H -azirin-3-amines 7(2,2-二取代的3-amino-2 H -azirines)被用作氨基酸合成子,用于制备中等大小的环二肽和水杨酸6和邻氨基苯甲酸19分别(方案2--4和5)。事实证明,将“叠氮基/恶唑酮法”用于合成含有α,α-二取代α-氨基酸的线性肽和酸催化的酰胺在DMF中于60°环化是一种极好的制备十元环的方法十肽和肽。在邻氨基苯甲酸衍生物的情况下,观察到跨环闭环反应(24 25)。较大的环被证明对水解极其敏感。
2,2-二取代的2 H -azirin-3-amines 7(2,2-二取代的3-amino-2 H -azirines)被用作氨基酸合成子,用于制备中等大小的环二肽和水杨酸6和邻氨基苯甲酸19分别(方案2--4和5)。事实证明,将“叠氮基/恶唑酮法”用于合成含有α,α-二取代α-氨基酸的线性肽和酸催化的酰胺在DMF中于60°环化是一种极好的制备十元环的方法十肽和肽。在邻氨基苯甲酸衍生物的情况下,观察到跨环闭环反应(24 25)。较大的环被证明对水解极其敏感。
N-benzoyl-2-methylalanines 3, obtained through condensation of aroyl chlorides 1 with sodium 2-methylalaninate are ortho-hydroxylated by the new Cu(0)/O2/trimethylamine N-oxide system. Acid hydrolysis of the so-obtained salicylamides 4 provides salicylic acids 5 in excellent yield. When the substrate contains three electron-releasing groups the yields are moderate.
Quantitative orthohydroxylation of N-benzoyl-2-methylalanine(1) occurs through its copper(II) salt oxidation by trimethylamine N-oxide; transitory formation of a CuIII species is proposed.
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(L-1)(TMAO)(2)] suggests that the oxygen transfer agent TMAO transfers the oxygen atom to copper(II), and (L-1)(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. (C) 2002 Elsevier Science B.V. All rights reserved.
REINAUD, OLIVIA;CAPDEVIELLE, PATRICE;MAUMY, MICHEL, J. CHEM. SOC. CHEM. COMMUN.,(1990) N, C. 566-568
作者:REINAUD, OLIVIA、CAPDEVIELLE, PATRICE、MAUMY, MICHEL
DOI:——
日期:——
CALCAGNI, A.;LUISI, G.;LUCENTE, G.;PINNEN, F.;ROSSI, D., INT. J. PEPTIDE AND PROTEIN RES., 36,(1990) N, C. 240-246
作者:CALCAGNI, A.、LUISI, G.、LUCENTE, G.、PINNEN, F.、ROSSI, D.