D A. Evans Diastereoaselective Hydrogenation: Acyclic Substrates Chem 206 Homoallylic Alcohols Evans, Morrissey Tetrahedron Lett. 26 6005(1985) The Premonensin Synthesis Rh(DIPHOS-4) 85: 15 disfavored 人| Eto2C CH3 CH Rh(+)(BINAP) 2(90%) A(1, 3)destabilization Evans, DiMare, JACS, 1986, 108, 2476 SOBS The lonomycin Synthesis CH3 CH3 Olefin Catalyst(H2 Pressure) syn: anti CH302C Rh(DIPHOS-4)(1000 psi) Rh(DIPHOS-4 a Ir(pyr)PCy3(15 psi, 2.5 mol%) Rh(DIPHOS-4)(1000 9:9 Diastereoselection: 94: 6(93%) with Dow, Shih, Zahler, Takacs, JACS 1990, 112, 5290OH CH3 R CH3 P Rh P Rh P P B A HO CH3 CH3 OTBS HO OTBS CH3 CH3 C CH3 R C R CH3 O H P Rh P CH2 C CH3 H C CH2 CH3 O H Rh H P P H H H2 H2 CH3 CH3 HO OTBS HO OTBS CH3 CH3 CH3 R CH3 OH OH CH3 R CH3 Me HO Me Me EtO2C OH CH3O2C CH3 CH3 CH3 CH3 H2 Me EtO2C Me HO Me C HO Me HO Me O OH Me O Me O Me Me Me Et Me OH HOOC O O Me OH OH OH CH3 CH3 CH3 CH3 CH3 CH3 CH3 H CH3 H CH3 O O H2 A A B CH3 CH3 CH3 CH3 CH3O2C OH Evans, DiMare, JACS, 1986, 108, 2476) } ✻ ✻ ✻ with Dow, Shih, Zahler, Takacs, JACS 1990, 112, 5290 Rh(DIPHOS-4)+ Diastereoselection: 94 : 6 (93%) The Ionomycin Synthesis The Premonensin Synthesis Rh + Catalyst Ratio 98 : 2 (90%) 65 : 35 85 : 15 Rh(+)(BINAP) + Rh(–)(BINAP) + Rh(DIPHOS-4) + anti syn Catalyst (H2 Pressure) syn : anti Rh(DIPHOS-4)+ (1000 psi) Ir(pyr)PCy3 + (15 psi, 2.5 mol%) Rh(DIPHOS-4)+ (1000 psi) 95 : 5 73 : 27 9 : 91 Olefin A(1,3) destabilization + + + + Homoallylic Alcohols Evans, Morrissey Tetrahedron Lett. 26 6005 (1985) syn anti D. A. Evans Diastereoaselective Hydrogenation: Acyclic Substrates Chem 206 favored disfavored