醛酯还原成醇

over anhydrous magnesium sulfate. Theether is evaporated and the lauryl alcohol distilled under diminished pressure.The yield is 60–70 g. (65–75 per cent of the theoretical amount) of a productboiling at 143–146°/18 mm. or 198–200°/135 mm.

【Organic Syntheses, Coll. Vol. 2,p.372; Vol. 10, p.62.】

金属在氮化物为催化剂

醛酮用0.5 mol的氮化铝锂催化时，可得到伯酮。

如仅用0.25mol并在低温下或降低氮化铝锂的催化能力，可使化学反应要到在醛的过渡阶段。

降低氮化铝锂催化能力可以降低催化化学反应的针对性。类似于的的法则是投身于各不相同分之一的水合三氯化铝或者投身于计算量的酮，取代氮化铝锂里面1-3个氮原子而成铝烷、或维蒂希氮化铝锂。如用维蒂希氮化铝锂催化α,β-糖类酮到α,β-糖类酮，若单用氮化铝锂催化，则得到饱和酮。

单纯使用氮化硼纳纳催化酮效果较差，若在Lewis硫酸如AlCl3, ZnCl2实际上下，催化能力大增，可如愿以偿的还酮，甚至可催化某些醛。

由氮硼化钠和酰托苯胺在α-甲托吡啶里面化学反应，分解的酰苯胺氮硼化钠是催化酮的有效地盐酸。其不同之处：化学反应操作方便，不需要水合条件，化学反应针对性好。

一、 LAH催化醛酮成伯酮下面

依靠LAH催化醛酮到伯酮是一个较慢速，成品较为方便的法则，一般意味著，酮托可在零下30℃下化学反应30 分钟需被催化。因此即使底物内有酰胺或其他一些引人注意的官能托实际上也没什么关系。

A dry, 500-mL, three-necked, round-bottomed flask isequipped with a 150-mL pressure-equalizing addition funnel, a reflux condensertopped with an inert atmosphere line, a glass stopper, and an egg-shapedmagnetic stirring bar. The flask is charged with lithium aluminum hydride (2.66g, 0.070 mol) and anhydrous ether (50 mL). The flask is cooled to 5°C in anice-water bath. A solution of (2R)-methyl4-(tert-butyldimethylsilyloxy)-2-(dimethylamino)cyclohex-3-enecarboxylate (22.4g, 0.072 mol) in ether (80 mL) is transferred to the addition funnel and addedover a 30-min period. The reaction mixture is stirred for another 15 min,diluted with ether (100 mL), and quenched by dropwise addition of water (9 mL).The ice-water bath is removed, the resulting gray suspension is allowed toreach room temperature, and the mixture is stirred vigorously for an additional60 min. The mixture is transferred to a 1.0-L Erlenmeyer flask and diluted with350 mL of ether. Anhydrous sodium sulfate (Na2 SO4) (60 g) is added,the suspension is stirred for 30 min, and filtered. The filter cake is washedtwice with ether (50 mL each time). The solvent is removed on a rotaryevaporator and the remaining volatile material is removed under high vacuum toafford 18.6 g (91%) of ((2S)-4-(tert-butyldimethylsilyloxy)-2-(dimethylamino)cyclohex-3-enyl)methanolas a viscous clear oil.

【Organic Syntheses, Coll. Vol.10, p.442; Vol. 78, p.160.】

二、三仲丁托硼氮化锂催化α,β-糖类酮到α,β-糖类酮下面

To a solution of3-(1H-benzoimidazol-5-yl)-acrylic acid methyl ester (50 mg in 1 ML drytetrahydrofuran) at -78.deg. C. was added 1.24 NL of a 1M solution of lithiumtri-sec-butylborohydride in tetrahydrofuran and the mixture stirred at -78.deg.C. for 4 hours followed by warming to -40.deg. C. for an additional 4 hours.

Thereaction was quenched by addition of aqueous methanol, concentrated in vacuoand purified by flash chromatography on silica gel (methylenechloride:methanol, 87:13) to give the title compound (44 mg).

三、硼氮化钠（钠）催化醛酮成伯酮下面

依靠硼氮化钠（钠）催化醛酮到伯酮操作较为人身安全，比较简单的法则，由于硼氮化钠的催化性过于爆冷，因此这类化学反应一般需要转回用餐。化学反应初始过渡阶段不要去蒸发，而是在液态下搅拌天内小时后在，再行蒸发缓缓转回，否则化学反应极容易喷出来。硼氮化钠在甲酮里面分解较较慢，这个化学反应尽量不要用甲酮做盐硫酸。

To a stirred suspension of 58.5g (300mmol) of dimethyl pyridine-2, 6-dicarboxylatein 800ml of anhydrous ethanol was added in portions 53.0g (1400mmol) of sodiumborohydride at 0°C, after stirring for 1h at 0°C, the ice bath was removed andthe ongoing exothermic reaction caused the solution to boil under reflux.Stirring was continued for 3h, then the solution was heated under reflux foranother 10h. The solvent was distilled off and the residue was digested with200ml of acetone. The acetone was distilled off; to the residue was added 200mlof a saturated aqueous solution of K2CO3 and the wholewas heated for 1h with a boiling water bath. The solvent was again distilledoff, the residue was dissolved in 800ml of water, and sodium chloride was addedin portions with stirring until a colorless precipitate was formed. The productwas extracted three times, each time with 150ml of chloroform, the combinedorganic phases were dried with MgSO4 and filtered. The solvent wasdistilled off to give 37.8g (91%)of desired product as colorless needles。

【Liebigs Ann.lRecueil 1997,707-720.】

四、NaBH4-ZnCl2催化酮下面

To a suspensionof ZnCl2 (80.36 g, 0.591 mol) in dry THF (1000 mL), NaBH4(11.2 g, 0.3043 mol) was added in portions at 0~5℃ under nitrogen. Themixture was stirred for 30 min at 20~25 ℃, The mixture was cooledto 0~5 ℃ and compound (S)-diethyl 2-(triisopropylsilyloxy)succinate(82 g, 0.2368 mol) was added dropwise at 0~5 ℃. Then the mixture waswarmed to 55~60 ℃ and stirred for 18 hours. Afterconfirming the completion of reaction by HPLC, The result reaction mixture was cooledto -15~-10 ℃. Water (213 mL) was added dropwise to quench the reaction at-15~-10 ℃. The reaction was aged for 3 h at 20~25 ℃.Charged celite (12.3 g) to the mixture and then the solid was removed byfiltration. The filtrate was concentrated under vacuum to remove THF. And thefilter cake was washed with CH2Cl2 (250×3mL). The combined organic layers were washed with water (200 mL) and themixture was separated and the organic layer was dried over Na2SO4.The solution was concentrated to give compound (S)-2-(triisopropylsilyloxy)butane-1,4-diol (44.68 g, 0.170 mol, yield 71.9%).

【Organic Syntheses, Coll. Vol. 7, p.530; Vol.63, p.136.】

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