Amino-acids and peptides. Part XXVIII. Anchimeric acceleration of the aminolysis of esters. The use of mono-esters of catechol in peptide synthesis
作者:J. H. Jones、G. T. Young
DOI:10.1039/j39680000436
日期:——
hypothesis that the aminolysis of esters can be accelerated by a neighbouring group capable of hydrogen-bonding to the incoming amine and accepting a proton from it has been supported by further evidence. Since such acceleration is not available for oxazolone formation (in which the nucleophile bears no hydrogen) it becomes possible to design fast, racemisation-free methods of peptide synthesis. Phthaloylglycine
进一步的证据支持了这样的假说,即酯的氨解可以被能够与引入的胺氢键结合并从中接受质子的相邻基团加速。由于这种加速不适用于恶唑酮的形成(亲核试剂不携带氢),因此有可能设计出快速,无消旋的肽合成方法。邻苯二甲酰基甘氨酸邻-羟基苯基酯和4,5-二氯-2-羟基苯基酯和苯甲酰基-L-亮氨酸邻酯-羟苯基酯,在室温下与甘氨酸乙酯迅速偶联;在最后一种情况(标准消旋试验)中,未发现外消旋体,并且与三乙胺一起,该酯未产生恶唑酮。当将相邻的羟基保护为苄基醚时,获得了一种不活泼的中间体,该中间体可以通过除去苄基,催化加氢或通过溴化氢在乙酸中的作用而被随意活化。