Amidic resonance not a barrier for transamidation of N-pivaloyl activated amides: catalyst, base and additive free conditions

Transamidation of twistless (twist angle (t) = 4.54 degrees) and resonance stabilized N-pivaloyl activated amides is demonstrated in the absence of a catalyst, base and additive. Furthermore, C-N (1.374 A) and C=O (1.222 A) bond lengths indicate the existence of amidic resonance; yet, transamidation is achieved at room temp-erature with alkyl amines in a short reaction time (0.5-2 h) with 60-97% yield. Amines bearing protic hydroxy and carboxylic acid groups were tolerated under the reaction conditions. Thus, our findings imply that N-pivaloyl-activated planar and resonance-stabilized amides are sufficiently reactive for nucleophilic addition.

Automated summary

In the absence of a catalyst, base and additive, transamidation of twistless and resonance stabilized N-pivaloyl activated amides was achieved at room temperature with alkyl amines in a short reaction time and high yield. The existence of amidic resonance was confirmed by the bond lengths of C-N and C=O. Amines bearing protic hydroxy and carboxylic acid groups were also found to be tolerated under the reaction conditions.