Pozdnev V F
Institute of Biological and Medical Chemistry, Academy of Medical Sciences, Moscow, Russia.
Int J Pept Protein Res. 1992 Nov;40(5):407-14.
Activation of carboxylic acids was achieved via dialkyl pyrocarbonates (ROCO)2O, R = C2H5, i-C3H7, sec-C4H9, tert.-C4H9) in aprotic solvents in the presence tertiary amines. A convenient procedure for the preparation of carboxylic acid anhydrides from carboxylic acids and di-tert.-butyl pyrocarbonate in the presence of pyridine is reported. Analogously, di-isopropyl- or diethyl pyrocarbonate may be used in the presence of N-methylmorpholine (triethylamine). With pyridine, di-isopropyl- or diethyl pyrocarbonate carboxylic acids form isopropyl- or ethyl esters, respectively. A wide variety of esters were prepared in good yields in a one-pot procedure from carboxylic acids, including N-protected amino acids, and alcohols or from phenols by means of di-tert.-butyl pyrocarbonate in the presence of pyridine (Boc2O-pyridine system). t-Butyl esters of carboxylic acids were obtained by the same procedure with 4-dimethylaminopyridine. In the absence of carboxylic acid, with 4-dimethylaminopyridine Boc2O and alcohols generate alkyl tert.-butyl carbonates.
在非质子溶剂中，在叔胺存在下，通过二烷基焦碳酸酯（(ROCO)₂O，R = C₂H₅、i-C₃H₇、sec-C₄H₉、tert.-C₄H₉）实现羧酸的活化。报道了一种在吡啶存在下由羧酸和二叔丁基焦碳酸酯制备羧酸酐的简便方法。类似地，在N-甲基吗啉（三乙胺）存在下可使用二异丙基或二乙基焦碳酸酯。与吡啶一起，二异丙基或二乙基焦碳酸酯与羧酸分别形成异丙酯或乙酯。通过一锅法，在吡啶存在下借助二叔丁基焦碳酸酯（Boc₂O-吡啶体系），由羧酸（包括N-保护的氨基酸）与醇或酚制备了多种产率良好的酯。用相同方法在4-二甲氨基吡啶存在下得到羧酸的叔丁酯。在没有羧酸的情况下，Boc₂O与醇在4-二甲氨基吡啶存在下生成烷基叔丁基碳酸酯。
