Gold(I)-catalyzed 6-endo-dig azide–yne cyclization : efficient access to 2H-1,3-oxazines

Denitrogenative 6-endo-dig azide-yne cyclization of α-propargyloxy-β-haloalkylazides was enabled by gold catalysis, thus providing 2H-1,3-oxazines. This rare cyclization mode in gold-catalyzed reactions of azide-yne substrates was demonstrated to be facilitated and controlled by electronic and resonance effects of the alkyne substituents. Molecular transformations of the as-prepared 2H-1,3-oxazines were also investigated.Ministry of Education (MOE)Nanyang Technological UniversityAccepted versionThis work was supported by funding from Ecole Polytechnique (for F. G.), Nanyang Technological University (for S. C.) and the Singapore Ministry of Education (Academic Research Fund Tier 2: MOE2013-T2-1-060 for S. C.). F. G. and S. C. are grateful to PHC Merlion grant (Project 5.02.15) for the support of this collaboration project