Nitrogenation of Alkynes with Nitrones to Prepare Functionalized [1,4]Oxazinones through Csp-Csp2 Bond Cleavage
Yu Zhao1, Li-Bing Yan1, Lin-Fen Liao1
1State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources (Ministry of Education of China), Collaborative Innovation Center for Guangxi Ethnic Medicine, School of Chemistry and Pharmaceutical Sciences, Guangxi Normal University, 15 Yu Cai Road, Guilin 541004, China.
Abstract:
Herein, we report a novel strategy of hypervalent iodine(III) compound-mediated selective Csp-Csp2 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.
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