Cycloadditions with Oxidopyrylium Ylides Photochemical Ring-Openings of Epoxides to Generate Ylides AEB Br2, MeOH 1)H3O° 150°ccH3CN,16h 12+2] cat HOAC/CH3CN Feldman, KS: Tetrahedron Lett. 1983, 24, 5585-5586. Sammes, P. G: Street, L.J. J. Chem. Soc., Chem. Commun. 1982. 1056- 35B-03 Ylides3/179311:16AM[2+2] • • hν PhH, pyrex Photochemical Ring-Openings of Epoxides to Generate Ylides PhH, pyrex hν 65% 34% 35% Feldman, K. S.; Tetrahedron Lett. 1983, 24, 5585-5586. Cycloadditions with Oxidopyrylium Ylides + - Br2, MeOH -45 °C 1) H3O+ 2) Ac2O / pyr 80% from furfuraldehyde 150 °C, CH3CN, 16h 61% DBN, CH2Cl2, RT 75% Me2CuLi (n = 1) pyrolysis cat. HOAc / CH3CN 150 °C, 16h 52% Sammes, P. G.; Street, L. J. J. Chem. Soc., Chem. Commun. 1982, 1056-1057 n = 1 O O CH3 O O O O O O CH3 O O O O O O O O O O A B A B O ( )n OH O OH R MeO OMe O O ( )n AcO O O ( )n AcO ( )n O H O O O AcO O H O Me O O O O OH O O 35B-03 Ylides 3/17/93 11:16 AM