Reaktionen von 2‐Benzoylacetamidin mit 1,3‐Dicarbonylverbindungen

Abstract

2‐Benzoylacetamidin (1) kondensiert mit Malondialdehyd‐Derivaten und 1,3‐Ketoaldehyden zu 2‐Amino‐3‐pyridyl‐phenylketonen. Aus 1 und 1,3‐Diketonen entstehen 2‐Phenacylpyrimidine, die in Lösung als chelatisierte Enole vorliegen.

Tautomeric Equilibria in Relation to Pi-Electron Delocalization

“…243 In the case of 2-benzoylacetamidate and 2-benzoylacetamidine in ethanolic solution, the chelated enolimine forms, HOsC(Ph)dCHsC(OEt)dNH and HOsC(Ph)dCHs C(NH 2 )dNH, respectively, are preferred instead. 244 Semiempirical and ab initio studies, 245 enriched recently by the detailed theoretical conformational analysis of Buemi et al,246 showed that the chelated enaminone tautomer is the most stable form for unsubstituted -aminoacrolein although the O-H‚‚ ‚N bridge (RAHB) in the other chelated enolimine tautomer, which is less stable by about 7 kcal mol -1 at the B3LYP/6-31G** level, seems to be the strongest bridge. The strength of the O-H‚‚‚N bridge is slightly greater than that of the O-H‚‚‚O bridge in malondialdehyde.…”