Silver(I)-catalyzed aminocyclization of 2,3-butadienyl and 3,4-pentadienyl carbamates: An efficient and stereoselective synthesis of 4-vinyl-2-oxazolidinones and 4-vinyltetrahydro-2H-1,3-oxazin-2-ones

Article abstract of DOI:10.1246/bcsj.68.1689

Silver(I) salts in combination with an appropriate base (mostly triethylamine) catalyzed the aminocyclization of N-substituted 2,3-butadienyl carbamates 1 (benzene, 50°C) to provide 4-vinyl-2-oxazolidinones 2 in good yields. The stereoselectivity (trans-2/cis-2) ranged from 1.4 for C₅-Me to >30 for C₅-phenyl, isopropenyl, and t-butyl derivatives. 3,4-Pentadienyl tosylcarbamates 3, the one-carbon higher homologues of 1, underwent a similar cyclization to give 4-vinyltetrahydro-2H-1,3-oxazin-2-one 4 in synthetically useful yields and in higher trans selectivities than 1.