The Synthesis of Furans The Synthesis of Furans ll CO2Et Intermolecular addition to a B-unsaturated carbonyls 60° O CHN2 160° hydrolysis --m 29% CO- CH Methyl vinhaticoate Storm, D L: Spencer, T.A. Tetrahedron Lett. 1967, 1865-1867 Spencer, T.A., et al. J. Am. Chem. Soc. 1967, 89, 5497-5499 Tandem intramolecular addition to alkynes-cyclization Cu(acac)2 Rh2(oAc)4 85% COCH3 Rh2(oAc)4 Padwa, A, et al. J. Org. Chem. 1990, 55, 414-416. CHO Tdebrandt, K: Debaerdemaeker, T; Friedrichsen, W. Tetrahedron Lett. 1988, 29, 2045-2046 35B-09 Ylides3/179311:18AMThe Synthesis of Furans + - CuSO4 160 °C 29% 2-methoxymethylenecholestanone-3 1) -OH 2) -CO2 Storm, D. L.; Spencer, T. A. Tetrahedron Lett. 1967, 1865-1867. Intermolecular addition to α,β-unsaturated carbonyls Tandem intramolecular addition to alkynes - cyclization Rh2(OAc)4 : 85% •• Rh2(OAc)4 Padwa, A., et al. J. Org. Chem. 1990, 55, 414-416. 52% Methyl vinhaticoate hydrolysis decarboxylation ~30% CuSO4 160 °C The Synthesis of Furans II Spencer, T. A., et. al. J. Am. Chem. Soc. 1967, 89, 5497-5499. Cu(acac)2 Hildebrandt, K.; Debaerdemaeker, T.; Friedrichsen, W. Tetrahedron Lett. 1988, 29, 2045-2046. 89% OMe O OMe O O EtO2C EtO2C Et O CHN2 O O O N2 Et Et O O Et O N2 O O O O O O O O O CHOCH3 H3C CO2CH3 H3C CO2CH3 EtO CHN2 O O CO2Et H3C CO2CH3 O CO2CH3 O O O O N2 CH3O O O O O CO2CH3 CH3O CO2CH3 O O O CH3O O CO2CH3 O O O CH3O HO 35B-09 Ylides 3/17/93 11:18 AM