D. A. Evans. K. Beaver Carbonyl Ylids: Dipolar Cycloaddition-2 Chem 206 Dipolar Cycloadditions: Carbonyl Ylides Reactions of Diazoimides: [3+2] addition-[4+2]retroaddit AcoMe N2Rh2(OAc). hCH3110°C CO2Et OCO,Et Me-N=C=o Dauben, JOC 1993 7635 Tigilane Skeleton 一 R=H OBI MeO2C Meo.c Me R2=H M Z= COMe, COmE N2 OMe Maier, M. E, Schoffling, B. Chem. Ber. 1989, 122, 1081-1087. Padwa. JOC 1995 2704 Lysergic Acid Skeleton Meoh H,80°c 85% CO2 Me 8-9 Me MeO.c Me MoC MeOH N-CO,Me Padwa. JOC 1995 6258 IPadwa,A; Hertzog, D L;Chinn, RL.Tetrahedron Lett.1989,30,4077-4080D. A. Evans, K. Beaver Chem 206 H H Dipolar Cycloadditions: Carbonyl Ylides O CO2Et N2 O H H H OAcMe Me H H O O CO2Et H AcO Me Me H H O CO2Et O Me Me AcO H Dauben, JOC 1993 7635 Tigilane Skeleton (86%) N N O OMe Me O N2 O Bz N Bz O N MeO2C OM Me N Bz N O MeO2C O Me H H Rh2 (pfb)4 N N O Et Me CO2Me O N N O Et Me CO2Me O O N O O CO2Me N2 Et N Me (95%) Padwa, JOC 1995 6258 Padwa, JOC 1995 2704 Lysergic Acid Skeleton Vindoline Skeleton (93%) N Z N2 O O R 2 R 2 R 1 Me N O O R 1 R 2 R 2 Me Z O N Me O Z R 1 R 2 R 2 O Z R 1 R 2 R 2 N Me O O O N2 N O CO2Me COCH3 MeO2C O MeO Padwa, A.; Hertzog, D. L.; Chinn, R. L. Tetrahedron Lett. 1989, 30, 4077-4080. 85% Rh2 (OAc)4 , PhH, 80 °C Maier, M. E.; Schöffling, B. Chem. Ber. 1989, 122, 1081-1087. Yields = 44-63% R 1 = H, OBn R 2 = H, Me Z = COMe, CO2Me Rh2 (OAc)4 PhCH3 , 110 °C – Me–N=C=O + – Reactions of Diazoimides: [3+2] addition – [4+2] retroaddition MeO2C CO2Me N O O Me O N O O Me O CO2Me MeO2C O CO2Me MeO2C OH Me N CO2Me Carbonyl Ylids: Dipolar Cycloaddition–2 O O Rh2 (OAc)4 Rh2 (OAc)4 MeOH H MeOH