In the past several years, tremendous advances have been made in non-classical routes for amide bond formation that involve transamidation and amidation reactions of activated amides and esters. These new methods enable the formation of extremely valuable amide bonds via transition-metal-catalyzed, transition-metal-free, or metal-free pathways by exploiting chemoselective acyl C–X (X = N, O) cleavage under mild conditions. In a broadest sense, these reactions overcome the formidable challenge of activating C–N/C–O bonds of amides or esters by rationally tackling n_N → π*_C=O delocalization in amides and n_O → π*_C=O donation in esters. In this account, we summarize the recent remarkable advances in the development of new methods for the synthesis of amides with a focus on (1) transition-metal/NHC-catalyzed C–N/C–O bond activation, (2) transition-metal-free highly selective cleavage of C–N/C–O bonds, (3) the development of new acyl-transfer reagents, and (4) other emerging methods.

中文翻译：

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非经典酰胺键的形成：通过选择性N–C / O–C裂解的活化酰胺和酯的酰胺基转移和酰胺化

在过去的几年中，在酰胺键形成的非经典途径中已经取得了巨大的进步，其中涉及活化酰胺和酯的转酰胺基化和酰胺化反应。这些新方法通过在温和条件下利用化学选择性酰基C–X（X = N，O）裂解，通过过渡金属催化，无过渡金属或无金属的途径，能够形成极为有价值的酰胺键。从最广泛的意义上讲，这些反应通过合理解决酰胺中的n _N →π* _{C = O}离域化和n _O →π* _{C = O的}离域化，克服了激活酰胺或酯的C–N / C–O键的艰巨挑战。捐赠酯类。因此，我们总结了开发酰胺合成新方法的最新进展，重点是（1）过渡金属/ NHC催化的C–N / C–O键活化，（2）过渡-无金属的C–N / C–O键的高选择性裂解，（3）新型酰基转移试剂的开发，以及（4）其他新兴方法。