Nitrogenation\nof Alkynes with Nitrones to Prepare\nFunctionalized [1,4]Oxazinones through Csp–Csp<sup>2</sup> Bond\nCleavage

Herein, we report a novel strategy of hypervalent iodine(III)\ncompound-mediated\nselective C<sub>sp</sub>–C<sub>sp</sub><sup>2</sup> bond cleavage\nof alkynes and CN/N–O bond cleavage of nitrones and\nrecombination of C–C/C–O/C–N multiple bonds to\naccess various functionalized [1,4]oxazinones bearing a vicinal carbon\nstereocenter in good yields and high diastereoselectivity. Mechanistic\nstudies revealed that the reaction undergoes a domino [4 + 3] cycloaddition,\n1,3-rearrangement of N–O bond, intramolecular cyclization,\ndearomatization, and rearomatization over four steps in a single flask.\nThe present method features good functional group tolerance, broad\nsubstrate scope, and C–C/CN/N–O multiple bonds\ncleavage and recombination.