Herein, we report a novel strategy of hypervalent iodine(III) compound-mediated selective C sp −C sp 2 bond cleavage of alkynes and C�N/N−O bond cleavage of nitrones and recombination of C−C/C−O/C−N multiple bonds to access various functionalized [1,4]oxazinones bearing a vicinal carbon stereocenter in good yields and high diastereoselectivity. Mechanistic studies revealed that the reaction undergoes a domino [4 + 3] cycloaddition, 1,3-rearrangement of N−O bond, intramolecular cyclization, dearomatization, and rearomatization over four steps in a single flask. The present method features good functional group tolerance, broad substrate scope, and C−C/C�N/N−O multiple bonds cleavage and recombination.