1.1.1醇醛缩合反应 (Aldol condensation) Definition: An aldol condensation is an organic reaction in which an enol or an enolate ion reacts with a carbonyl compound to form a 3 hydroxyaldehyde or B-hydroxyketone, followed by a dehydration to give a conjugated enone. 定义:含有α-H的醛或酮,在稀碱或稀酸(通常为稀碱)的 催化作用下,一分子醛或酮的c氢原子加到另一分子醛 或酮)的氧原子上,其余部分加到羰基碳上,生成⑧羟基 醛或酮)的反应,该增长碳链的反应称为醇(羟)醛(酮)缩 合反应
1.1.1 醇醛缩合反应 (Aldol condensation) Definition: An aldol condensation is an organic reaction in which an enol or an enolate ion reacts with a carbonyl compound to form a β- hydroxyaldehyde or β-hydroxyketone, followed by a dehydration to give a conjugated enone. 定义：含有α-H的醛或酮，在稀碱或稀酸(通常为稀碱)的 催化作用下，一分子醛(或酮)的-氢原子加到另一分子醛 (或酮)的氧原子上，其余部分加到羰基碳上，生成β-羟基 醛(或酮)的反应，该增长碳链的反应称为醇(羟)醛(酮)缩 合反应
Formation of conjugated enone Aldol condensations are important in organic synthesis, providing a good way to form carbon- carbon bonds It involves the nucleophilic addition of a ketone enolate to an aldehyde to form a B-hydroxy ketone or"aldol(aldehyde alcohol), a structural unit found in many naturally occurring molecules and pharmaceuticals. RR RR O H或 H2o RH2C-CC--CR 2 R-CH2-C-R R-C-C-C-C-R OH H Reaction mechanisms
Formation of conjugated enone R CH2 C R' O R H2 C C C C R ' R' R OH O C C CR' R - H2O R' O RH2C 2 OH 或 H H Aldol condensations are important in organic synthesis, providing a good way to form carbon– carbon bonds. It involves the nucleophilic addition of a ketone enolate to an aldehyde to form a β-hydroxy ketone, or “aldol” (aldehyde + alcohol), a structural unit found in many naturally occurring molecules and pharmaceuticals. Reaction mechanisms
Mechanism A: Base catalyzed Inorganic Base: NaoH Na, CO3, NaH etc. Organic Base: EtoNa, BuLi, etc. H B R-C—C C-C—R-R—C=C—R 慢 ⊙ O R R RO 快 2 R—C-C+R-8-R÷R-C-C-C-C—R OO H R RO B RR B R-C-C=C-c—R R-C-C-C-C—R -HO OH H 产物不稳定
Inorganic Base: NaOH, Na2CO3, NaH, etc. Organic Base: EtONa, BuLi, etc. Mechanism A：Base catalyzed R H2 C C C C R ' R O R H ' O R H2 C C R' O + R H C C R' O 快 R H2 C C C C R ' R OH R H ' O R H2 C C C C R ' R ' R O B： B： -H2 O 产 物 不 稳 定 R H2 C C R' O R H C C R' O R C H C R' O B： 慢
Mechanism B: Acid catalyzed Acid: H2 SO4 Hcl, TsOH, etc. R-CH2-C-R.H+ R—CH2-C—R R—CH2—C-R O OH HO RR O 2 R一CH3-C—R+R—HC=C—R=~R-C-C-C—C—R HO OH OH R H2O R R-C—C RICH C—R C=C-CR ④OH2 RH2C R
Acid: H2SO4, HCl, TsOH, etc. Mechanism B：Acid catalyzed R H2 C C C H C R ' R ' R OH2 O C C CR' R H - H2 O -H O R' RH2 C R CH2 C R' O R CH2 C R' OH R CH2 C R' HO H + R HC C R' OH R CH3 C R' HO R H2 C C C H C R ' R ' R OH O +
1.1.1.1 Self-Condensation between two same molecules NaoH CH3 CH2 CH2-- -CHO 25°C OH CH2 CH3 2CH3 CH CH2CHO NaoH CH3CH2CH2CH=C一CHO 80°C CH2CH Al(t-BuO) H2PO + OH 般用碱性催化剂
1.1.1.1 Self-Condensation CH3 CH2 CH2 CH OH H C CHO CH2 CH3 CH3CH2CH2CH C CHO CH2 CH3 2CH3CH2CH2CHO NaOH 25℃ NaOH 80℃ OH O O O H3 PO4 O + Al(t-BuO) 4 一般用碱性催化剂 between two same molecules