D. A. Evans Enantioselective C=O Addition: Noyori Catalyst Chem 115 Catalytic Asymmetric Carbonyl Addition The Catalytic Cycle place with chiral controller the catalyst Noyori& co-workers, J. Am. Chem. Soc. 1986, 108, 6072 JAm.chem.Soc.1989,111,4028 Review: Noyori Angew. Chem. Int. Ed. 1991, 30, 49 E- Et 2Zn the catalyst (DAlB-ZI 59-97% C6H5CHO 98%ee.: Catalyst must be sterically hindered so that association is precluded p-CICBH4CHO EtZ 93%ee 93%ee. n-C6H13CHO 61%ee. 4 RO-ZnR ne method is catalytic in aminoalcohol a Two zinc species per aldehyde are involved in the alkylation step a Product is taken out of the picture by aggregation 19A01-Et2Zn-11/1900149PM00 00 0000 0000 0000 Review: Noyori Angew. Chem. Int. Ed. 1991, 30, 49 the catalyst ■ Two zinc species per aldehyde are involved in the alkylation step. ■ Product is taken out of the picture by aggregation 4 ■ The method is catalytic in aminoalcohol. D. A. Evans Enantioselective C=O Addition: Noyori Catalyst Chem 115 Noyori & co-workers, J. Am. Chem. Soc. 1986, 108, 6072. replace with chiral controller Catalytic Asymmetric Carbonyl Addition 98% e.e. ■ Catalyst must be sterically hindered so that association is precluded 91% e.e. 93% e.e. 93% e.e. 96% e.e. 90% e.e. 61% e.e. Et2Zn Me2Zn Et2Zn Et2Zn Et2Zn Et2Zn Et2Zn C6H5CHO " p-ClC6H4CHO p-MeOC6H4CHO Cinnamyl PhCH2CH2CHO n-C6H13CHO 0°C, toluene 59 - 97% Ar–CHO + R2’Zn J. Am. Chem. Soc. 1989, 111, 4028. the catalyst the catalyst Et2Zn 90-98% ee RDS The Catalytic Cycle (DAIB-Zn) Zn R Zn I I C O R R H Me Me N H Me Me Me O Zn H Et Me Me N H Me Ar R’ OH Me Me O Zn H Et O C H Zn Et Et Zn Et C Et O H O Zn Et H H N Me Me Me Me Me O C H Et H O Zn Et H H O N Me Me Me Me Me Me Me N H Me Me Me O Zn H Et Zn–Et O C H R' O Zn O Zn Zn O O Zn R R R R'O ZnR R' Zn R R' R' O R R' O R' Zn R O Zn Zn O R R' R' R Zn Et H H O N Me Me Me Me Me 19A-01-Et2Zn-1 1/19/00 1:49 PM