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The synthesis of fused dihydropyran isoxazole derivatives has been developed by employing an intermolecular inverse‐electron‐demand Diels‐Alder reaction of readily available alkylidene isoxazol‐5‐ones with unactivated alkenes. The reaction was promoted by inexpensive and commercially available BF3 ⋅ Et2O without the use of metal Lewis acids. This cycloaddition transformation could proceed under mild conditions with broad substrate scope, providing a variety of bicyclic 5,6‐dihydro‐4H‐pyrano[3,2‐d]isoxazoles. [ABSTRACT FROM AUTHOR]

The synthesis of spiroisoxazoline molecules has been developed via anodic oxidative dearomatization of 4‐methoxybenzyl oximes. The reaction is thought to proceed through 5‐exo C−O bond‐forming cyclization of oxime radicals with arenes on the basis of cyclic voltammetry studies. Moreover, spiroisoxazolines can be built directly from readily available carbonyl tethered phenolics via an oximation/dearomatization cascade. Using this spiroisoxazolization as the key step, the first total synthesis of xanthoisoxazoline B has been achieved in three steps. [ABSTRACT FROM AUTHOR]