D. A. Evans Enantioselective C=O Addition: Dialkylzinc Addn Scope Chem 115 Improved Selectivity with Aliphatic Aldehydes Scope of the DAlB Catalyst Soai, J. Org. Chem. 1991, 56, 4264 (S)catalyst (S)catalyst (6%) Et2Zn 98%ee RCHo+ 0°c, hexane 70-100% (S)catalyst 91%ee 88%ee 78%ee 95%ee93%ee (S)catalyst Lepicidin Application The reaction functions in complex systems Bu3Sn (n-Pen)2Zn 85%ee the catalyst (S)catalyst Evans, Black, JACS 1993, 115, 44974513 OTIPS Et2Zn 60%ee OTES Et24 0°c, hexane Review. Noyon Angew. Chem. Int. Ed. 1991, 30, 49 10.:1(98%) 19A-03-Et2Zn-Scope 1/19/00 1: 49 PM88% ee 78% ee 95% ee 93% ee Improved Selectivity with Aliphatic Aldehydes Soai, J. Org. Chem. 1991, 56, 4264 (6%) RCHO + Et2Zn 0 °C, hexane 70 - 100% 60% ee Et2Zn (S) catalyst Review: Noyori Angew. Chem. Int. Ed. 1991, 30, 49 (S) catalyst Et2Zn 90% ee (S) catalyst (n-Pen)2Zn 85% ee 96% ee Et2Zn (S) catalyst (S) catalyst Me2Zn 91% ee 98% ee Et2Zn (S) catalyst Scope of the DAIB Catalyst (S) catalyst D. A. Evans Enantioselective C=O Addition: Dialkylzinc Addn Scope Chem 115 Lepicidin Application: The reaction functions in complex systems 3 9 Et2Zn, 3 3 15 15 11 diastereoselection 10:1 (98%) 21 the catalyst 21 21 0 °C, hexane Evans, Black, JACS 1993, 115, 44974513 H O OH Et Me OH O Zn Me2 N Me Ph N O Bu Et Zn Me Bu R Et OH O O n-Bu H H O O H Me H Me O OR OR O O Me Et H H H H H MeO OTIPS OTES O O H H O OH H Bu3Sn Me H O Et OH MeO SnBu3 OTIPS OTES O Me C5H11 OH O H H OH O Bu3Sn H n-Bu SnBu3 H H Zn H O OH H N Bu Me O Et Bu n-Bu Ph 19A-03-Et2Zn-Scope 1/19/00 1:49 PM