Cycloadditions with Oxidopyrylium Ylides-Syntheses Cycloadditions with Oxidopyrylium Ylides-Syntheses Cryptofauronol Fauronyl Acetate 阝 Bulnes 50°C,24h 150°C,20h 1)Pd/C, EtoH 2) Ac20 l pyr CHCN CH3CN 2) MeAl TiCl4 Na, Et20 84% CrO3-pyr 46%(3sep5 Ac2O, NaOAc△ 83% smn:0mxP门1 Sammes. P.G. Street L J. J. Chem. Soc. Chem. Commun. 1983. 666-668 ammes, P G: Street, L J: Whitby, R.J. J. Chem. Soc. Perkin Trans. I. 1986, 281-289 35B-05 Ylides3/16/934:43PMCycloadditions with Oxidopyrylium Ylides - Syntheses 150 °C, 24 h CH3CN 1) 1 O2-MeOH then PPh3 2) Ac2O / pyr. Cryptofauronol Fauronyl Acetate 1) iPrMgI, CuBr•Me2S 2) MeMgI TiCl4 Ac2O, NaOAc, ∆ 46% (3 steps) 84% 83% + Sammes, P. G.; Street, L. J. J. Chem. Soc. Chem. Commun. 1983, 666-668. Sammes, P. G.; Street, L. J.; Whitby, R. J. J. Chem. Soc. Perkin Trans. I. 1986, 281-289. Sammes, P. G.; Street, L. J. J. Chem. Soc. Chem. Commun. 1983, 666-668. Sammes, P. G.; Street, L. J.; Whitby, R. J. J. Chem. Soc. Perkin Trans. I. 1986, 281-289. Me2C=PPh3 Na, Et CrO3-pyr 2O 1) Pd / C, EtOH 2) MeMgI 3)SOCl2 150 °C, 20 h CH3CN 1:5 β:α-Me β-Bulnesene Cycloadditions with Oxidopyrylium Ylides - Syntheses H CH3 O O AcO O H O CH3 Me H O CH3 Cl H HO CH3 H O CH3 H CH3 O O AcO H H OH O O OH O H3C O OH H3C O CH3 CH3 CH3 OH O CH3 CH3 OAc O H H OAc O O H3C O CH3 TiCl3 CH3 O CH3 iPr 35B-05 Ylides 3/16/93 4:43 PM