Equivalence of Oxirane Ring-Opening Intermediate to Generation of Carbonyl Ylides via the Ring-opening Carbene-Carbonyl Lone Pair Interaction Intermediates of epoxides isooctane A H3CO2C HcHO k2 125°C,15min HoC cOaCH Ratios CO2CH3 n 40(9,175) 125℃c,10da HcHO 40(10.5.230 - c(co,CH3 C(CO2 CH3)2 bach, W: Brokatzky, J; Fritz, H. Angew. Chem. Int. Ed. Engl. 1980, 19, 47-48. atzky, J: Eberbach, W. Tetrahedron Letf. 1980, 21, 4909-4912 Ratio k2 lk2 3 Photochemical ring-openings gave a complex mixture of products was due in part to a scrambling of the ylide Huisgen, R; de March, P J. J. Am. Chem. Soc. 1982, 104, 4952, 4953. See Brokatzky-Geiger, J. Eberbach, W. Heterocycles. 1983, 20, 1519-1524 Tetrahedron Lett. 1 35B-02Ydes3/16/933:23PMPhotochemical ring-openings gave a complex mixture of products in overall low yields. This was due in part to a scrambling of the ylide substituents. See Brokatzky-Geiger, J.; Eberbach, W. Heterocycles. 1983, 20, 1519-1524. Tetrahedron Lett. 1984, 25, 1137-1140. Eberbach, W.; Brokatzky, J.; Fritz, H. Angew. Chem. Int. Ed. Engl. 1980, 19, 47-48. Brokatzky, J.; Eberbach, W. Tetrahedron Lett. 1980, 21, 4909-4912. 91 34 11 66 100 89 100 100 9 75 30 97 57 73 75 isooctane 40 (9, 175) 30 (9, 175) 72 (5, 170) 58 (7, 215) 55 (8, 240) 40 (10.5, 230) Ratios H CO2Me R 1 2 1 3 5 10 n conversion (hours, °C) yield A B C C A B Generation of Carbonyl Ylides Via the Ring-Opening of Epoxides + - - + - + (CH3O2C)2C-N2 + C6H5-CHO Oxirane 3.3 3.0 Ratio k2 / k2 Huisgen, R.; de March, P. J. J. Am. Chem. Soc. 1982, 104, 4952, 4953. PhCHO PhCHO Equivalence of Oxirane Ring-Opening Intermediate to Carbene-Carbonyl Lone Pair Interaction Intermediates + - 125 °C, 15 min. 125 °C, 10 days Starting material k2' k2 C6H5 O CO2CH3 H CO2CH3 O C(CO2CH3)2 C6H5 H C(CO2CH3)2 H O H CO2CH3 H3CO2C H C6H5 CH3O2C CO2CH3 CH3O OCH3 N2 O O O C(CO2CH3)2 H O H C6H5 C6H5 O ( )n Ph CN O O ( )n O Ph CN O ( )n O Ph CN O Ph H R O Ph H R R CN CN O Ph R H CN O O ( )n Ph CN R R R H H H H H 35B-02 Ylides 3/16/93 3:23 PM