Mechanistic aspects of the application of 2-ethyl-7-hydroxybenzisoxazolium fluoroborate, 1, to peptide synthesis are presented. Optimal conditions are described for the formation of 3-acyloxy-2-hydroxy-N-ethylbenzamides, 2, from 1 and peptide acids. Amines are found to react with esters, 2, as their 2-oxyanion conjugate bases. Racemization in model systems is found to occur via oxazolones, and the low racemizing tendency of the esters, 2, is shown to result from a unique internal buffering effect.

中文翻译：

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苯并异恶唑鎓盐的肽合成—Ⅱ：2-乙基-7-羟基苯并恶唑鎓氟硼酸酯的活化化学；3-酰氧基-2-羟基-N-乙基苯甲酰胺的偶联化学

介绍了将2-乙基-7-羟基苯并恶唑鎓氟硼酸盐1应用于肽合成的机理。最佳条件的形成-3-酰氧基-2-羟基-N- ethylbenzamides，描述2，从1种肽酸。发现胺与作为其2-氧阴离子共轭碱的酯2反应。发现模型系统中的外消旋化是通过恶唑酮发生的，酯2的低外消旋化趋势表明是由独特的内部缓冲作用导致的。