1559rch23409-42210/19/0519:50Page412 EQA 412 chapter 23 ESTER ENOLATES AND THE CLAISEN CONDENSATON This oth OCH.CH D HC-CHCOCH-CH (C.H.C- OCH.CH CH:CH2 O OCH.CH COCH.CH COCH,CH OCH-CH 25.The second ester.(CH)CHCOCH.should be nt in stabl product from Claisen from the first ester.Side reaction (condensation of first ester with itself): 0 2CH.CH.CO.CH,CH.CH.CCHCO.CH CH 26.Analyze as you did for Problem 24.Claisen"means 1.NaOCH,CH CH,CH,OH.2.HH.O. CHCO.CH.CH,-CH.Co.CH.CH C.H.CCHCO.CH.CH,C.H.CO.CH.CH,+C.H.CH.CO.CH.CH c COzCHCH [Problem 24(e)!](d) (e) (f) (g) (h) (i) O B 25. The second ester, (CH3)2CHCOCH3, should be present in excess because (1) it does not form a stable product from Claisen condensation with itself and (2) it will be able to preferentially react with enolate ions from the first ester. Side reaction (condensation of first ester with itself): 26. Analyze as you did for Problem 24. “Claisen” means 1. NaOCH2CH3, CH3CH2OH, 2. H, H2O. (a) (b) (c) [Problem 24(e)!] Claisen CO2CH2CH3 CO2CH2CH3 CO2CH2CH3 CH3 CH3 O Claisen C6H5C CHCO2CH2CH3 C6H5CO2CH2CH3 C6H5CH2CO2CH2CH3 C6H5 O Claisen CH2C CHCO2CH2CH3 CH2CO2CH2CH3 O 2 2 CH3CH2CO2CH3 CH3CH2CCHCO2CH3 CH3 NaOCH3, CH3OH O OCH2CH3 OCH2CH3 O O O O C C COCH2CH3 COCH2CH3 O O O O CHCOCH2CH3 CH3CH2 C6H5C O O HC CHCOCH2CH3 C6H5 O O O O This other possible product is not stable and will not be isolated. CH3 COCH2CH3 O O C CH3 OCH2CH3 O O C OCH2CH3 412 • Chapter 23 ESTER ENOLATES AND THE CLAISEN CONDENSATION 1559T_ch23_409-422 10/19/05 19:50 Page 412