Iodine(III)-Mediated Keto-oximation of -Alkynyl Hydroxylamines: A Route to 3-Acyl Isoxazolines and 1,2-Oxazines.

An intramolecular iodine(III)-mediated keto-oximation of -alkynyl hydroxylamines offers rapid and straightforward access to 3-acyl Δ-isoxazolines and 1,2-oxazines. This approach features mild, metal-free, and aerobic reaction conditions with good functional group tolerance. Moreover, the synthetic utility of this method is demonstrated by the synthesis of unique structural motifs such as isoxazolidine, 3-vinyl isoxazoline, and 2,5-diphenylpyrazine derivatives by the conversion of 3-acyl Δ-isoxazolines, thereby showcasing its efficiency and applicability in synthetic chemistry.

Leveraging Alkyne-Oximium Cyclization for the Stereoselective Synthesis of Isoxazolidine.

A TMSOTf-mediated highly diastereoselective synthesis of isoxazolidine bearing three contiguous stereocenters is described. This method utilizes -propargyl hydroxylamines as a novel building block for the rapid assembly of the isoxazolidines via alkyne-oximium cyclization. The strategy could be used in the synthesis of enantiomerically enriched isoxazolidines.