D. A. Evans Enolate Alkylation: Chiral Ester Enolates Chem 206 Chiral Ester Enolates Helmchen, Angew. Chem. Int Ed. 1981, 20, 207-208 Chiral B-Keto Ester Enolates CO2t-Bu LICHIP ( LICHIPA) THF. HMPA Me?HC NH o Me? N o OMe SOpH toluene Me?HC HMPT H Lio Me the steacie tea eto e of pe c (El-enolate (z-enolate El(+) addend Yield RatIo(A: B) Me- THF 63% 96: 04 Me、Meso2Ph Me so,Ph Koga,JACS1984.10627182719 Me- HMPT57%0199 THF 48%99:01 HMPT 77%15:85 Chiral B-Keto Ester Dienolates 旧nC14H2g98515 (4) n-C14H29- 06 94 enolate contamination Helmchen, Angew. Chem. Int Ed. 1984, 23, 60-61 Me Me ou En,CN Major diastereomer Helmchen Tet. Lett. 1983. 24. 1235-1238 Helmchen Tet. Lett. 1983. 24. 3213-3216 t-BuLi E什+)=Me-,E+,BnBr SOpH Me. Me so PhH astereoselection 98% △ Rationalize the stereochemical outcome of reaction Rato,93:7(74%) Helmchen. Tet. Lett. 1985. 26. 3319-3322 Schlessinger, Tet. Lett. 1988, 29, 1489-1492Li N Me Me (LiCHIPA) THF N H SO2Ph O LiO Me Me Me Me Me H Me SO2Ph N O O Me Me Me Me Me R H LiCHIPA O Me Me Me Me Me LiO Me N SO2Ph H H El SO2Ph N X O O Me Me Me Me H H O Me Me Me Me Me O N SO2Ph Br NH OMe Me2HC O CO2t-Bu H El O Me Me Me O N X SO2Ph Me KO-t-Bu Me2HC N O OMe Li O RO H O Me Me Me O N X SO2Ph H H THF CO2t-Bu Me2HC N O OMe El HMPT Me–I Me–I OLi Me Me Me N O A El N OMe Me2HC O CO2t-Bu Bn-Br THF Bn-Br HMPT t-BuLi THF B O N Me Me Me O HMPT O Me Me Me N O Me D. A. Evans Enolate Alkylation: Chiral Ester Enolates Chem 206 Koga, JACS 1984, 106, 2718-2719 Chiral Ester Enolates THF, HMPA 4:1 Helmchen, Angew. Chem. Int.Ed. 1981, 20, 207-208 (E)-enolate (Z)-enolate (E) enolate El(+) Ratio n-C14H29–I 98.5:1.5 (Z) n-C14H29–I 06:94 enolate contamination Helmchen, Angew. Chem. Int.Ed. 1984, 23, 60-61 Helmchen,Tet. Lett. 1983, 24, 1235-1238 Helmchen,Tet. Lett. 1983, 24, 3213-3216 Helmchen,Tet. Lett. 1985, 26, 3319-3322 Ratio, 93:7 (74%) Chiral b-Keto Ester Enolates LDA toluene 01:99 El(+) Yield Ratio (A:B) 63% addend 57% 96:04 99:01 77% 48% 15:85 Rationalize the effect of HMPA on the stereochemical outcome of reaction. Chiral b-Keto Ester Dienolates Major diastereomer El(+) El(+) El(+) E(+) = Me–I, Et–I, Bn–Br diastereoselection 98% Rationalize the stereochemical outcome of reaction. Schlessinger,Tet. Lett. 1988, 29, 1489-1492