Intramolecular cyclization to fused pyranoisoxazoles and molecular packing motifs identification through X-ray structural studies

The present work describes intramolecular cyclization of 4-(hydroxyamino)-2-oxo-6-aryl-N-(substituted)-2H-pyran-3-carboxamides (1a-e) under the basic condition to yield fused pyranoisoxazoles (2a-e). The X-ray structural studies delineate a network of non-covalent forces that provided a molecular packing motif to generate a reproducible stacking pattern towards column scaffold formation in the pyranoisoxazole crystal system. A one-pot method to yield pyranoisoxazole system through intramolecular ring closure and crystal packing reveals a common molecular stacking framework to yield column scaffold mediated by molecular packing motifs. [Display omitted] •One-pot synthesis of pyranoisoxazole through intramolecular ring closure.•Molecular packing motif identified, which uses intramolecular C-H…O interaction mediated planarity followed by intermolecular stacking.•Crystal packing reveals aromatic stacking in column framework driven by molecular packing motif.