20.2A Crossed claisen condensations(交叉克菜森缩合) Crossed Claisen condensations are possible when one ester component has no a ydrogens and is, therefore unable to undergo self-condensation ), CH3 OCH, CH,+ CH3 COoCH Ethyl benzoate no a -hydrogen OCH2 CH3 Ethyl benzoylacetate (60%)
20.2A Crossed Claisen condensations (交叉克莱森缩合） Crossed Claisen condensations are possible when one ester component has no α- hydrogens and is, therefore, unable to undergo self-condensation. O OCH2CH3 + CH3COOC2H5 1) NaOCH2CH3 2) H + O H2 C O OCH2CH3 Ethyl benzoate Ethyl benzoylacetate (60%) no -hydrogen
OCH2CH3 )NaoCH,2CH CH2COC2H5 CrHsoCoCHs no a-hydrogen OCH2 CH3 Ethyl phenylacetate Diethyl carbonate 苯乙酸乙酯 甲酸二乙酯 Diethyl phenylmalonate (65%) 苯基丙二酸乙酯 1)NaoCH, CH3 CH2COC2 H5 H3 CH2CO C-OCH2 CH3 no a-hydrogen Ethyl phenylacetate Diethyl oxalate 苯乙酸乙酯 草酸二乙酯 c—cocH2CH OCH2CH
1) NaOCH2CH3 2) H + no -hydrogen CH2COC2H5 O + C2H5OCOC2H5 O Ethyl phenylacetate Diethyl carbonate 苯 乙 酸 乙 酯 甲 酸 二 乙 酯 O O OCH2CH3 OCH2CH3 Diethyl phenylmalonate (65%) 苯 基 丙 二 酸 乙 酯 1) NaOCH2CH3 2) H + no -hydrogen CH2COC2H5 O + Ethyl phenylacetate Diethyl oxalate 苯 乙 酸 乙 酯 草 酸 二 乙 酯 C O O COCH2CH3 OCH2CH3 O C O H3CH2CO OCH2CH3 O
20.2B Acylation of other carbanions(其它负碳离子酰基化) a NaOH,CH 3 Nat 1)H3CH2Co OCH2CH3 2) OCH2 CH3 (67%)
20.2B Acylation of other carbanions(其它负碳离子酰基化） O NaOCH2CH3 O - Na + O O O OCH2CH3 (67%) O O 1) H3CH2CO OCH2CH3 2) H+
20. 3 The acetoacetic ester synthesis: Synthesis of substituted acetones R—X CH CH2tR or CH3 cH—R R—X CH CCH,COOCH,CH
20.3 The Acetoacetic ester synthesis: Synthesis of substituted acetones CH3 O CH2 R or CH3 O CH R R CH3CCH2COOCH2CH3 O R X R X