藥物合成反應(yīng)第四章縮合反應(yīng)-閱讀頁(yè)
2025-06-10 18:21本頁(yè)面
【正文】 b羥烷基、 b羰烷基化反應(yīng) 一 b羥烷基化反應(yīng) FC反應(yīng) ? 2. 反應(yīng)機(jī)理 C H 3 C HC H 2 C H 2 O H C H 3 C HC H 2 C H 2O H苯環(huán)連在取代基多的 C上 S n C l 2 / C S 2 1 0 0 C+ ( 4 0 % )C 6 H 5C H 3 C HC H 2OC H 3 C HC H 2 C H 2 O HC H 2 ? （ 1）區(qū)域選擇性 ? （ 2）立體選擇性 ? 構(gòu)型反轉(zhuǎn) ? （ 3）制備環(huán)內(nèi)酯 二、 b羰烷基化反應(yīng) Michael加成反應(yīng) 反應(yīng)機(jī)理 : +δδδδ+O HC H 3OOC H 3HHOOC H 3OOC H 3COC H 2 C H+C H 2O HC H 3OOC H 3COC H 2 C HHC H 3OOC H 2 C H3CO△C H 3 H 2 OOOδδ+OOC H 3OOC H 3OC H 2C H 3OOC H 2 COC H 2HO H H（ 3）影響因素 ? 1) the nucleophile (Michael donor) can be derived by the deprotonation of CHactivated pounds such as aldehydes, ketones, nitriles, βdicarbonyl pounds, etc. as well as by the deprotonation of heteroatoms。 ? （ 4）應(yīng)用 第四節(jié) 亞甲基化反應(yīng) 一 羰基烯化反應(yīng) （ 1）反應(yīng)通式及機(jī)理 +n C 4 H 8 L i / E t ON 2 , 2 5 0 C( C 6 H 5 ) 3 C H 3P B rC 6 H 62 5 0 C ( C 6 H 5 ) 3 P C H 3 B rR 39。 R 39。 + OC H 2HOHC( C 6 H 5 ) 3 PCRHOHC( C 6 H 5 ) 3 PCRR C ( C 6 H 5 ) 3 P? （ 2）影響因素 ? the ylides are water as well as oxygensensitive； ? the phosphorous ylides chemoselectively react with aldehydes (fast) and ketones (slow), other carbonyl groups (., esters, amides) remain intact during the reaction。 ? ③ the choice of solvent is crucial and the use of dipolar aprotic solvents (., DMF) is advantageous, since protic solvents inhibit the last 1,2elimination step。 Y = O, NR。 ? (2) due to the electrophilic nature of the reagent, the rate of cyclopropanation is faster with more electron rich alkenes. However, highly substituted alkenes may react slower due to the increased steric hindrance。 ? (4) when the alkene has functional groups containing heteroatoms (., OH, OAc, OMe, OBn, NHR), a strong directing effect is observed and the delivery of the alkylidene occurs from the face of the double bond having the closer proximity of the functional g
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