Recyclable Hypervalent Iodine(III) Reagent Iodosodilactone as an Efficient Coupling Reagent for Direct Esterification, Amidation, and Peptide Coupling

A hypervalent iodine(III) reagent plays a novel role as an efficient coupling reagent to promote the direct condensation between carboxylic acids and alcohols or amines to provide esters, macrocyclic lactones, amides, as well as peptides without racemization. The regeneration of iodosodilactone (1) can also be readily achieved. The intermediate acyloxyphosphonium ion C from the activation of a carboxylic acid is thought to be involved in the present esterification reaction.

高价碘(III)试剂（hypervalent iodine(III) reagent）作为高效偶联试剂，展现出全新的应用效能，可介导羧酸与醇或胺间的直接缩合反应，制备得到无外消旋化的酯、大环内酯、酰胺及肽类化合物。碘代二内酯（1）（iodosodilactone (1)）的再生过程同样简便易行。现有研究表明，羧酸活化产生的中间体酰氧基鏻离子（acyloxyphosphonium ion）C参与了本次酯化反应。