4-Arylmethylisoxazol-5-one Derivatives − Novel Synthesis, Structural Studies, and Supramolecular Self-Assembly through Resonance-Assisted Hydrogen Bonding

Abstract

Arylmethylisoxazol-5-ones (3) were prepared by a new mild reductive procedure using tertiary amines containing a flexible N−CH−CH grouping. A concurrent process competed with the reduction, yielding fair quantities of chain-elongation products (4). The X-ray structures of two selected arylmethyl derivatives are reported and are shown to have the expected different tautomeric arrangements. The unusual features of the NH-tautomer (3e) were interpreted in terms of the RAHB (resonance-assisted hydrogen bond) model and its relative stability was investigated by ab initio and DFT calculations.