15.3、 Robinson annulation环合反应 Micheal addition aldol condensation CH3 CH H OH CH HRc 65% H3C 1.5-diketone Mechanism: step 1: Michael addition H-OH CH3 CH CH H OH H CH H3C 24
24 15．3、Robinson Annulation环合反应 Micheal addition + Aldol condensation O CH3 H + C CH C H3C O H H OH CH3 O 65% O OH O C CH C H3C O H H CH3 H OH O CH3 C H C H3C O O CH3 C H3C O 1,5-diketone Mechanism: step 1: Michael addition CH3 H 1 5
Robinson annulation: mechanism -suite step 2: Intramolecular aldol reaction CH CH3 CH3 CH C=O 0 0 HC OH HO H OH OH step 3: Dehydration CH3 CH3 CH3 OH OH H 25
25 Robinson Annulation: Mechanism –Suite O CH 3 C H 2 C O HO H O CH 3 O H 2 C CH 3 O O H OH CH 3 O OH OH step 2: Intramolecular aldol reaction CH 3 O OH H H OH CH 3 O OH H CH 3 O OH step 3: Dehydration
Robinson annulation: further examples Cooc 2n5 COOCH NaOC2H5 00 OMe OCH3 OH EtOH
26 Robinson Annulation: further examples O COOC 2 H 5 O NaOC 2 H 5 O COOC 2 H 5 OCH 3 O O OH EtOH O OMe O O O
15.4、酯的酰化反应 808 H3C-C-CH3 Base: -H3c-C-CH3 +H2C=C-CHj3 acetone (pKa=20) enolate of acetone 809 H3C--C-OCHa Base:=H2C-C-OCH3 H2C=C-OCH3 methyl acetate enolate of methyl ester (pKa=24) R-C-0R←RC0-R R一c-CHC-R
27 15.4、酯的酰化反应 C CH3 H3C O C CH3 H3C O H3C C OCH3 O R C O O R C CH2C O O R' acetone (pKa = 20) + Base: C CH3 O methyl acetate (pKa = 24) + Base: H2C H2C C OCH3 O C OCH3 O H2C enolate of acetone enolate of methyl ester R CO R O R
15.4.1、 The claisen condensation缩合 β-酮酯的合成 两分子酯在碱作用下加成, 脱去一分子醇,生成β-酮酯的反应。 )c2H50 H2C-CfoC H3C-C-C-C-OC2H5 H2 β- keto ester H2C-C-OC2Hs (C2HSOH 乙” 乙酰乙酸乙酯
28 15.4.1、The Claisen Condensation 缩合： β-酮酯的合成 H3C C OC2H5 O C C OC2H5 H2 O H3C C O C2H5OH 两分子酯在碱作用下加成, 脱去一分子醇，生成β-酮酯的反应。 1) C2H5O 2) H a β-keto ester H2C C OC2H5 + H O "三乙” 乙酰乙酸乙酯