Keto–enol tautomerism of β‐ketoamides and characterization of a sterically crowded α‐amido‐β‐ketoamide

Abstract

Abstract An α‐amido‐β‐ketoamide ( 1 ) and two α‐alkyl‐β‐ketoamides ( 2 and 3 ) were prepared and characterized, and their keto–enol tautomerism was studied by H/ 13 C NMR spectroscopy. Both α‐alkyl‐β‐ketoamides 2 and 3 are in the keto form in CDCl 3 , and their enol forms cannot be detected by 1 H/ 13 C NMR spectroscopy, whereas the α‐amido‐β‐ketoamide 1 shows both keto and enol forms in CDCl 3 with an experimental K E of 0.70 at 298 K. Copyright © 2002 John Wiley & Sons, Ltd.