| 99% |
Stage #1: para-methylacetophenone With C23H20BrMnNO3P In isopropanol for 0.166667h; Inert atmosphere; Schlenk technique;
Stage #2: With potassium-t-butoxide In isopropanol at 60℃; for 3h; Inert atmosphere; Schlenk technique; |
|
| 99% |
With palladium; hydrogen In methanol at 35℃; for 20h; |
2 Example 2: Synthesis of 1- (4-methylphenyl) -1-ethanol
To a solvent of methanol (2 mL) with PdNPore (2.7 mg, 5 mol%) catalyst, p-methylphenylacetaldehyde (60.1 mg, 0.5 mmol) as a substrate was added, and the mixture was placed on a magnetic stirrer for reaction at 35 ° C for 20 hours. Chromatography (silica gel, 200-300 mesh; developing solvent, petroleum ether, ethyl acetate) gave 67.4 mg of 1- (4-methylphenyl) -1-ethanol with a yield of 99%. |
| 99% |
With C17H29Cl2NO4PdSi; hydrogen In toluene at 30℃; for 1h; Autoclave; High pressure; |
2.2 Standard Procedure fortheHydrogenationofSubstrates
General procedure: Hydrogenation reactions were carried out in a stainless steelautoclave Parr reactor equipped with an internal cooling system,a temperature control unit and a sampling valve. In atypical experiment, the reactor was pre-heated, evacuatedand flushed with nitrogen and cooled to room temperature.A solution of styrene (0.25ml, 2.10mmol) and complexPd3 (0.0014g, 0.0027mmol) in toluene (20ml) was thenintroduced using a cannula. The reactor was then purgedwith hydrogen gas several times, and then the desired pressureand reaction temperature set and stirred for the specifiedtime. At the end of the reaction period, the reactor wasthen cooled, the gas supply closed and excess hydrogen gasvented off. The samples were then collected for GC analysesusing a syringe equipped with 0.45μm micro filtersand analysed by a Varian CP-3800 GC (ZB-5HT Column30m × 0.25mm × 0.1μm) to establish percentage conversions.The percentage conversions were calculated by comparisonof the substrate peak areas to those of the products,assuming 100% mass balance. The kinetics reactionswere done through monitoring the change in substrate consumptionover time at regular intervals. The rate constantswere then derived from graphical plots of ln[substrate]0/[substrate]t versus time. The catalysis products were identi |
| 99% |
With methanol; sodium tetrahydridoborate at 0 - 20℃; for 0.666667h; Inert atmosphere; |
|
| 99% |
With Hantzsch ester; isopropanol; sodium hydroxide In acetonitrile for 36h; Inert atmosphere; Irradiation; |
2 Example 2 The hydrogen transfer reaction of p-methylacetophenone catalyzed by a nitrogen-containing heterocyclic thiol monovalent copper compound
Add 1mmoL p-methylacetophenone, 0.1mmoLNaOH, 0.3mmoLHEH and 4mg of nitrogen-containing heterocyclic mercaptan monovalent copper compound into a dry reflux reaction tube with a magnetic stirrer, and then add 5mL, volume ratio of 3:1 The mixed solution of anhydrous isopropanol and acetonitrile is stirred for reaction. Replace with helium gas for 3 times during the reaction. Use blue LEDs as the light source for catalytic reaction. Stir the reaction for 36 hours. After completion, add 5 mL of water, extract with 3×5 mL of ethyl acetate, combine the organic phases, and dry with anhydrous magnesium sulfate. After filtering, the filtrate is concentrated by rotary evaporation, and the target product is obtained by silica gel column chromatography. The yield of the target product is 99%. |
| 98% |
With sodium tetrahydridoborate In ethanol at 20℃; |
|
| 98.7% |
With sodium tetrahydridoborate In ethanol for 5h; |
|
| 98% |
With mesoporous silica; sodium cyanotrihydridoborate for 0.0222222h; Neat (no solvent); Microwave irradiation; regioselective reaction; |
|
| 98% |
With 2BH4(1-)*Zn(2+)*Cl2Na2 In acetonitrile at 20℃; for 1.33333h; |
2.4. Typical Procedure for the Reduction of Ketones withZn(BH4)2/2NaCl System in CH3CN
General procedure: In a round-bottomed flask (10 mL), equipped with a magneticstirrer bar, a solution of acetophenone (0.121 g, l mmol) was prepared in CH3CN(3 mL). To this solution, Zn(BH4)2/2NaCl (0.210 g,1 mmol) was added. The resulting mixture was stirred at room temperature for 60 min. The reaction was monitored by TLC(eluent; Hexane/EtOAc: 10/1). After completion of the reaction, distilled water (5 mL) was added to the reaction mixture and stirred for 5 min. The mixture was extracted with CH2Cl2 (3 ×8 mL) and dried over anhydrous Na2SO4. Evaporation of the solvent followed column chromatography of the resulting crude material over silica gel (eluent; Hexane/EtOAc: 10/1) afforded crystals of 1-phenylethanol (0.l1 g, 93 % yield,Table 2, entry 11). |
| 98% |
With bis(acetonitrile)bis(2,4-pentanedionato)ruthenium(II); isopropanol; sodium hydroxide at 80℃; for 8h; |
|
| 98% |
With ethanol; (dcype)Ni(COD) In neat (no solvent) at 130℃; for 36h; |
|
| 98% |
With copper(II) bis(2,4-pentanedionate); hydrogen In methanol at 90℃; for 20h; Autoclave; |
|
| 97% |
With C53H46ClN3P2Ru; potassium isopropoxide; isopropanol at 82℃; for 0.0111111h; |
|
| 97% |
With sodium hypophosphite monohydrate; 5%-palladium/activated carbon; tetra-n-butyl-ammonium chloride In 2-methyltetrahydrofuran; lithium hydroxide monohydrate at 60℃; for 1.5h; Schlenk technique; |
General procedure for the ketone reduction in alcohol 1-19a,c (method A)
General procedure: In a Schlenk tube (10mL), a solution of ketone compound (1mmol), tetrabutylammonium chloride (20mg, 72μmol, 7mol%), and Pd/C 5% wt (50% in water) (55mg, 26μmol, 2.6mol%) in 2-MeTHF (1mL) was stirred at room temperature (20°C) for 10-20min. To this mixture was added a solution of sodium hypophosphite monohydrate (424mg, 4mmol, 4equiv) in water (2.5mL). The reaction mixture was heated at 60°C. After dilution in CH2Cl2 (10mL), water (10mL) was added. The aqueous phase was extracted with CH2Cl2 (2×20mL). The combined organic layers were dried (Na2SO4), filtered, and concentrated. Purification by flash chromatography on silica gel was performed for products 4a, 5a, 10a, 12a, 15a, and 19c. 4.2.1 4-(1-Hydroxyethyl)benzoic acid methyl ester [84851-56-9]11d (1a) (0021) Procedure A; 2.7h; colorless oil (170mg, 94%). 1H NMR (300MHz, CDCl3) δ (ppm)=1.51 (d, 3H, J=6.5Hz, CH3), 1.84 (brs, 1H, OH), 3.91 (s, 3H, OCH3), 4.97 (q, 1H, J=6.5Hz, CH-OH), 7.45 (d, 2H, J=8.3Hz, Harom), 8.02 (d, 2H, J=8.3Hz, Harom). |
| 97% |
With sodium tetrahydridoborate In methanol at 15 - 35℃; |
1.1 Step 1
In a 100 m L three-necked flask, add 6.7 g of 4-methylacetophenone and 30 ml of methanol, stir, cool with ice water, add 2.28 g of sodium borohydride, and react at 15 -35 °C for 3 to 5 h. The reaction solution was neutralized with 2.0 mol/L of sulfuric acid, methanol was evaporated under reduced pressure, and dichloromethane (40 m L×2) was evaporated. The organic phase was washed with water, dried over anhydrous sodium sulfate and filtered.Concentration under reduced pressure gave 1-(4-methylphenyl)-1-ethanol (I) 6.56 g as a colorless oily liquid, yield 97%. |
| 97% |
With C30H24Cl2N2PRhS; isopropanol; potassium hydroxide at 80℃; for 6h; Inert atmosphere; |
2.4. Procedure for catalytic transfer hydrogenation
General procedure: In a typical experiment the ketone (2 mmol), KOH (0.02 mmol), andcomplex 1 (0.005 mmol) were added to degassed iPrOH (5 mL), and themixture was stirred at 80 C in an inert atmosphere for 6 h. The reactionwas then monitored at various time intervals by the use of GC. After thereaction was complete, iPrOH was removed on a rotary evaporator, andthe resulting semisolid was extracted with diethyl ether (5 × 5 mL). Thecombined liquid phase was analyzed by GC using undecane as an internalstandard. |
| 96% |
With sodium tetrahydridoborate; sodium hydrogen sulphate In acetonitrile at 20℃; for 0.333333h; |
|
| 96% |
With sodium tetrahydridoborate In methanol at 20℃; for 2h; |
|
| 96% |
Stage #1: para-methylacetophenone With C107H90Cl2N10P4Ru2(2+)*2Cl(1-) In isopropanol at 82℃; for 0.166667h; Inert atmosphere;
Stage #2: With potassium isopropoxide In isopropanol for 2h; Inert atmosphere; |
|
| 96% |
With isopropanol; sodium hydroxide for 3h; Inert atmosphere; Schlenk technique; Reflux; |
2.3 General procedure for transfer hydrogenation of ketones catalyzed by 4
General procedure: Under nitrogen atmosphere, a mixture of ketone (2 mmol), catalyst 4 (0.008 mmol), and 2-propanol (17.6 mL) was stirred at 82°C. After 5 min, 2.4 mL of 0.1 M NaOH (0.24 mmol) solution in 2-propanol was introduced to initiate the reaction, and the reaction mixture was stirred at refluxing temperature. At the specified time, 0.1 mL of the reaction mixture was filtered through a short pad of celite to remove the complex catalyst, and immediately diluted with 0.2 mL of 2-propanol. The filtrate was used for GC analysis. After the reaction was finished, the mixture was condensed under reduced pressure and subject to flash silica gel column chromatography to afford the alcohol product (detected under 254 nm UV light or by alkaline potassium permanganate solution; eluent: petroleum ether (60-90 °C)/ethyl acetate = 10:1 or petroleum ether (30-60 °C)/dichloromethane= 1:1, v/v). The alcohol products were identified by comparison with the authentic sample through NMR and GC analyses. |
| 95% |
With sodium tetrahydridoborate; pyrographite In tetrahydrofuran; lithium hydroxide monohydrate at 20℃; for 0.25h; |
|
| 95% |
With lithium iodide In methanol at 30℃; for 0.416667h; |
|
| 95% |
With Zn(2+)*2BH4(1-)*C6H7NO In acetonitrile at 20℃; for 0.5h; chemoselective reaction; |
Reduction of Benzaldehyde to Benzyl alcoholwith [Zn(BH4)2(2-MeOpy)]
General procedure: A Typical ProcedureIn a round-bottomed flask (10 mL),equipped with a magnetic stirrer, a solution ofbanzaldehye (0.106 g, l mmol) in CH3CN (3 mL)was prepared. The complex reducing agent (0.1 g,0.5 mmol) was then added and the mixture wasstirred at room temperature. TLC monitored theprogress of the reaction (eluent; Hexane/EtOAc: 9/1). After completion of the reaction within 1 min, asolution of 5% HCl (5 mL) was added to the reactionmixture and stirred for 5 min. The mixture was extracted with CH2Cl2 (3 × 10 mL) and dried overthe anhydrous sodium sulfate. Evaporation of thesolvent and short column chromatography of theresulting crude material over silica gel (0.015-0.040mm) by eluent of (Hexane/EtOAc: 9/1) afforded thepure liquid benzyl alcohol (0.105 g, 98% yield) |
| 95% |
With [Re(NH{CH2CH2P(iPr2)}2)(CO)3]Br; potassium-t-butoxide; hydrogen In toluene at 70℃; for 17h; Inert atmosphere; Glovebox; Autoclave; |
|
| 95% |
With pyridine; potassium-t-butoxide; isopropanol In toluene at 135℃; for 12h; Inert atmosphere; Schlenk technique; |
|
| 95% |
Stage #1: para-methylacetophenone With C44H44CuN2P2(1+)*F6P(1-) In toluene at 25℃; for 1h; Inert atmosphere;
Stage #2: With sodium hydroxide In methanol; lithium hydroxide monohydrate Inert atmosphere; |
3. Typical procedure for catalytic hydrosilylation of ketones
General procedure: Under nitrogen atmosphere the copper based catalyst 1 (8 7 mmg0.01 mmol), tBuOK ( 5 6 mmg0.05 mmol) and toluene (3 mL) were placed in a tube equipped with a Teflon coated magnetic stirring bar. T he mixture was stirred at 25 °C for 15 min and then polymethylhydrosiloxane (PMHS, 0.0 9 m L, 1.5 mmol mmol) was injected. After 15mins, ketone (0.5 mmol) was introduced and the mixture was stirred at 25 °C for therequired reaction time. The mixture was quenched with MeOH (1 mL) and 10%NaOH solution (3 mL), and the mixture was stirred for 4 h. T he mixture was extractedwith ethyl acetate (5 mL × 3) and the combined organic layer was washed with waterand saturated sodium chloride solution, dried over anhydrous Na2SO4. the solvent was removed under vacuum and the residue was purified by flash chromatography (silica gel) to afford the desired product. All the product alcohols were analyzed by 1H NMR, 13C NMR, or GC analysis. |
| 95% |
With C84H102Cl2Fe2N14O13(2+)*2Cl(1-); isopropanol; potassium hydroxide at 80 - 85℃; for 12h; Inert atmosphere; Schlenk technique; |
|
| 94% |
With sodium tetrahydridoborate In lithium hydroxide monohydrate for 0.00694444h; microwave irradiation; |
|
| 94% |
Stage #1: para-methylacetophenone With sodium tetrahydridoborate In methanol at 0 - 20℃; Inert atmosphere;
Stage #2: With lithium hydroxide monohydrate |
|
| 94% |
With isopropanol; lithium tert-butylate at 180℃; for 0.5h; |
|
| 94% |
With isopropanol at 85℃; for 24h; Inert atmosphere; |
|
| 94% |
With ammonium sulfate||mascagnite||(NH4)2SO4||SO4(NH4)2; sodium tetrahydridoborate In tetrahydrofuran; lithium hydroxide monohydrate at 20℃; for 2h; |
A typical procedure for reduction of ketones with the NaBH4/(NH4)2SO4 system in wet-THF
General procedure: In a round-bottomed flask (10 mL)equipped with a magnetic stirrer and a condenser,a solution of acetophenone (0.12 g, l mmol) in THF-H2O (3:0.6 mL) was prepared and NaBH4(0.038 g,1 mmol) and (NH4)2SO4(0.234 g, 2 mmol) wereadded and the mixture was stirred at roomtemperature for 90 minutes. TLC monitored theprogress of the reaction (Hexane/EtOAc: 9/1). Aftercompletion of the reaction distilled water (5 mL)was added to the reaction mixture and it was stirredfor an additional 1 minute. The mixture wasextracted with CH2Cl2(3×10 mL) and dried overanhydrous sodium sulfate. Evaporation of thesolvent and short column chromatography of theresulting crude material over sil-ica gel (Hexane/EtOAc: 9/1) afforded the pure crystals of 1-phenylethanol (0.l1 g, 96% yield, Table 1, entry 8). |
| 94% |
With zinc(II) tetrahydroborate In lithium hydroxide monohydrate for 0.0333333h; Microwave irradiation; Green chemistry; |
Reduction of benzaldehydewith Zn(BH4)2/Microwave Irradiation, A typical procedure
General procedure: Zn(BH4)2was prepared from ZnCl4 (5.452g, 0.04 mol) and NaBH4(3.177 g, 0.084 mol)according to an available procedure in the literature11.In a round-bottomed flask (10 mL) charged withdistilled water (5 mL), Zn(BH4)2(0.095 g, 1mmol)and benzaldehyde (0.106 g, 1 mmol) was added.After fitting the flask to the external condenser atthe inside of the oven, the mixture was irradiatedwitha microwave oven (30% power amplitude, 300 W)for60 sec. The progress of the reaction wasmonitored by TLC(eluent; CH2Cl2). At the end of thereduction, distilledwater (5 mL) was added to thereaction mixture and it wasthen extracted withCH2Cl2(2×10 mL). The combined extracts were dried over anhydrous sodium sulfate. Evaporationofthe solvent afforded the pure liquid benzyl alcohol(0.102 g, 95%). |
| 94% |
With Cp*Ir(6,6'-dionato-2,2'-bipyridine)(H2O); hydrogen In tert-Amyl alcohol at 30℃; for 12h; Green chemistry; |
4.2. General procedure for catalytic hydrogenation of 2
General procedure: To an oven-dried 5 mL round-bottom flask were added ketone (1 mmol), cat. 7 (2.7 mg, 0.5 mol %) and tert-amyl alcohol (1 mL). Next, vacuum was applied to the flask followed by filling with H2 gas and keeping the flask attached to a balloon filled with H2 gas. The mixture was heated at 30 °C for 12 h. After completion of the reaction, the solvent was removed by evaporation under reduced pressure. The alcohols were isolated and purified by filtering a hexanes/ethyl acetate (5:1) solution of the crude product through a pad of silica gel, and then removing the solvent under reduced pressure. The conversion and purity of the alcohol products was assessed using NMR spectroscopy. |
| 94% |
With (2-aminomethylpyridine); manganese(I) pentacarbonyl bromide; potassium-t-butoxide; hydrogen In tetrahydrofuran at 120℃; for 12h; Autoclave; chemoselective reaction; |
4.3. Representative procedure for the catalytic hydrogenation reactions
General procedure: A 4 ml glass vial was sequentially charged with solid [Mn(CO)5Br](0.015 0.030 mmol), the substrate (0.5 mmol), 2-picolylamine(0.015 0.030 mmol), and a magnetic stirring bar. The reaction componentswere then dissolved in THF (2 ml) or 1,4-dioxane (2 ml)whereupon the resulting yellow solution was then gently stirred(200 rpm) for a period of 5 min. Whilst stirring, the glass vial was sealed with the septum cap. Hereafter, solid t-BuOK (0.015 0.030 mmol) was added to the reaction mixture upon which the reaction vessel was again sealed with a septum cap which was then penetrated with a needle.Notably, the base addition was carried out without stirring. After that,the glass vial was placed in a drilled aluminum liner which was promptly transferred into the 300 ml autoclave. Once tightly sealed, the latter was purged five times with H2 (20 bar per cycle) before being pressurized to the desired value. The autoclave was then placed on a pre-heated stirring plate and heated up to the required reaction temperature. On completion of the hydrogenation reaction, the autoclave was allowed to reach room temperature. Afterwards, the remaining gas was slowlyreleased upon which the reaction mixture was degassed through brieflystirring on air. Finally, n-dodecane (12 mg) or n-hexadecane (20 mg)were added and an aliquot of 30 μl was taken from the solution, mixedwith acetone (1 ml) whereupon the resulting solution was analyzed byGC. |
| 93% |
With sodium tetrahydridoborate In methanol at 0 - 20℃; for 4h; |
|
| 93% |
With isopropanol; potassium hydroxide at 85℃; for 6h; |
|
| 93% |
With sodium tetrahydridoborate; diammonium oxalate In acetonitrile for 1.16667h; Reflux; |
|
| 93% |
With zinc(II) tetrahydroborate In tetrahydrofuran; lithium hydroxide monohydrate at 20℃; for 1.66667h; |
|
| 93% |
With aluminum(III) oxide; zinc(II) tetrahydroborate In tetrahydrofuran at 20℃; for 3h; chemoselective reaction; |
A typical procedure for reduction of ketones to alcohols with the Zn(BH4)2/Al2O3 system in THF
General procedure: In a round-bottomed flask (10 mL) equipped with a magnetic stirrer, a solution ofacetophenone (0.121 g, 1 mmol) in THF (3 mL) was prepared. To this solution, Zn(BH4)2(0.095 g, 1 mmol) and then neutral Al2O3 (0.101 g, 1 mmol) were added. The resulting mixturewas stirred at room temperature for 60 min. The progress of the reaction was monitoredby TLC (eluent, CCl4/Et2O: 5/2). After completion of the reaction, distilled water (1 mL) wasadded to the reaction mixture and then stirring was continued for an additional 5 min. Themixture was extracted with CH2Cl2 (3×8 mL) and dried over anhydrous sodium sulfate. Evaporationof the solvent and short column chromatography of the resulting crude material overabove mentioned silica gel afforded pure crystals of 1-phenylethanol (0.11 g, 93 % yield,Table IV, entry 2) |
| 93% |
With sodium tetrahydridoborate In tetrahydrofuran at 20℃; for 1.66667h; |
|
| 93% |
With C31H35Cl2IrN2O2; potassium-t-butoxide; isopropanol at 82℃; for 24h; Inert atmosphere; Schlenk technique; |
General procedure for hydrogen transformation.
General procedure: Ketone(1.0 mmol) or imine (1.0 mmol), tBuOK (0.1 mmol) and cata-lyst (0.01 mmol) were weighed into an oven-dried Schlenk flask.Dry iPrOH (3.0 mL) was added to the flask, and the mixture was refluxed for the time specified under nitrogen. The reaction wascooled, and an aliquot was filtered through a pad of Celite andthe crude product was purified by column chromatography using petroleum ether and ethyl acetate. The analytical data of all products are consistent with the data reported in literature [2,3]. |
| 93% |
With C37H28Cl2N5PRu; isopropanol; sodium hydroxide at 82℃; for 0.0333333h; Inert atmosphere; |
|
| 93% |
With phenylsilane; C14H15MnN5O3(1+)*BF4(1-) In acetonitrile at 80℃; for 3h; |
|
| 93% |
With Cp*Ir(6,6'-dionato-2,2'-bipyridine)(H2O); isopropanol at 82℃; for 6h; Inert atmosphere; Green chemistry; |
3 1-p-tolylethanol
The 4-methyl acetophenone (134 mg, 1.0 mmol), cat. [Ir] (1.1 mg, 0 . 002 mmol, 0.2 μM %) and isopropyl alcohol (5 ml) are added to the 25 ml Kjeldahl tube, N2Protection Cooling to room temperature, rotary evaporation to remove the solvent, then through the column chromatography (developing solvent: petroleum ether/ethyl acetate) to obtain the pure target compound, yield: 93% |
| 93% |
With C28H25BrMnN2O3P; potassium-t-butoxide; hydrogen In tert-Amyl alcohol at 60℃; for 20h; Glovebox; Autoclave; |
|
| 93% |
With fac-[Mn((1,2-bis(di-isopropylphosphino)ethane))(CO)3(CH2CH2CH3)]; hydrogen In diethyl ether at 25℃; for 24h; Inert atmosphere; Glovebox; Autoclave; |
|
| 92% |
Stage #1: para-methylacetophenone With Cp(CO)2Mn(IMes); diphenylsilane In toluene at 25℃; for 1h; Schlenk technique; Inert atmosphere; UV-irradiation;
Stage #2: With sodium hydroxide In methanol; toluene at 20℃; for 2h; Schlenk technique; Inert atmosphere; |
|
| 92% |
With C56H55ClN3P2Ru(1+)*F6P(1-); potassium 2-methyl-2-butoxide In isopropanol at 20 - 80℃; for 1.5h; Schlenk technique; Inert atmosphere; |
|
| 92% |
With zinc(II) tetrahydroborate In acetonitrile at 20℃; for 1.5h; Sonication; |
Typical procedure for the reduction of carbonylcompounds with Zn(BH4)2 under ultrasonicirradiation in CH3CN
General procedure: In a round-bottomed flask (10 mL) equipped with a magnetic stirrer bar, a solution of benzaldehyde (0.1061 g, l mmol) was prepared inCH3CN (3 mL). To this solution Zn(BH4)2 (0.095 g,1mmol) was added. The resulting mixture was stirredunder ultrasonic waves at room temperature for 5min. The progress of the reduction reaction wasmonitored by TLC (eluent:CCl4/Et2O:5/2). Aftercompletion of the reaction, distilled water (5 mL)was added to the reaction mixture and stirred for 5min. The mixture was extracted with CH2Cl2 (3×10mL) and dried over anhydrous Na2SO4. Evaporationof the solvent afforded pure benzyl alcohol (0.102g, 95% yield). |
| 92% |
With C44H50Cl4N4Ru2; isopropanol; sodium hydroxide at 40 - 80℃; for 2h; Inert atmosphere; |
|
| 92% |
With C22H27BrN2ORu; isopropanol; potassium hydroxide for 1.5h; Reflux; Inert atmosphere; |
|
| 91% |
With formic acid; macrocyclic Ni(II); ammsnium formate at 100℃; for 2.5h; |
|
| 91% |
With RuBr(MeCOO)(PPh3)2(N-BzBzTh); sodium tertiary butoxide In isopropanol at 82℃; for 30h; Inert atmosphere; |
|
| 91% |
With [IrH(1,5-cyclooctadiene)Cl(HCN(i-Pr)CHCN(C2H4PPh2))]PF6; isopropanol; potassium hydroxide for 6h; Inert atmosphere; |
General procedure for Transfer Hydrogenation of Acetophenones and enones
General procedure: To a 10 mL Schlenk tube equipped with a stir bar was charged with ketone (1 mmol), KOH (0.05 mmol), and iPrOH (3 mL). The mixture was degassed by bubbling N2, and 0.1 mol % of catalyst 2 for entry 1-10 and 0.5 mol% of 2 for entry 11-19, was added under a steady flow of N2. After removal any inorganic salts by filtration, all the volatiles were removed under reduced pressure. The pure product could be obtained by silica gel chromatography (ethyl acetate/hexane). The identity of these products have been confirmed by comparisons of the obtained spectra with those previously reported. |
| 91% |
With RuBr(CH<SUB>3</SUB>COO)<SUB>2</SUB>(PPh<SUB>3</SUB>)<SUB>2</SUB>(3-benzylbenzothiazol-2-ylidene); isopropanol; sodium tertiary butoxide at 82℃; for 30h; Inert atmosphere; Schlenk technique; |
|
| 91% |
With hydrogen at 80℃; |
|
| 91% |
With manganese(I) pentacarbonyl bromide; potassium-t-butoxide; Ethane-1,2-diamine In isopropanol at 80℃; for 3h; |
2.1. Representative procedure for transfer hydrogenation reaction ofacetophenone
General procedure: To a solution of acetophenone (58 μL, 0.5 mmol) in 2-propanol (0.5 mL) was added a stock solution of manganese pentacarbonyl bromide (0.5 mL, 0.005 mol·L-1; 2.7 mg, 0.010 mmol, in 2 mL 2-propanol)followed, in this order, by a stock solution of ethylenediamine (0.5 mL,0.005 mol·L-1; 1.0 μL, 0.0125 mmol, in 2.5 mL 2-propanol) and tBuOK (0.5 mL, 0.010 mol·L-1; 2.4 mg, 0.020 mmol, in 2 mL 2-propanol). The reaction mixture was stirred for 3 h at 80 °C in an oil bath. The solution was then filtered through a small pad of silica (2 cm in a Pasteur pip-ette). The silica was washed with ethyl acetate. The filtrate was evaporated and the conversion was determined by 1H NMR. The crude residue was then puried by column chromatography (SiO 2 , mixture of petroleum ether/ethyl acetate or dietyl ether as eluent. Enantiomeric excesses were determined by GC analyses performedon GC-2014 (Shimadzu) 2010 apparatus equipped with Supelco beta-DEX 120 column (30 m × 0.25 mm). The determination of the absoluteconguration was done by comparison with (S)-alcohol obtained bykinetic resolution of racemic alcohols with Novozym 435 (CandidaAntarctica Lipase B) and by comparison of the retention times with the literature [32-34]. |
| 91% |
With C44H40ClN2NiP2(1+)*F6P(1-); hydrogen; potassium hydroxide In isopropanol at 120℃; for 12h; Autoclave; |
3. Typical procedure for hydrogenation
General procedure: Ni-based catalyst (0.01 mmol) was added into a dried autoclave (100 mL). After the addition of fresh distilled iPrOH (20 mL), the autoclave was purged with H2 (30 bar) five times. The mixture was then stirred under 30 bar H2 for 1 h. After releasing the H2 gas in a fumehood, KOH in iPrOH (1 M, 0.2 mL) and ketone (0.5 mmol) were sequentially introduced through an injection port. The autoclave was then pressurized to 40 bar H2 and the reaction mixture stirred at 120 °C for 12 h. After cooling down to room temperature and subsequently releasing the H2 pressure in a fumehood, the mixture was concentrated and purified by chromatograph on a silica-gel column. The conversion of the product was determined by GC. |
| 91% |
With [Cp*Ir(2,2'-bpyO)(OH)][Na]; hydrogen In lithium hydroxide monohydrate at 30℃; for 12h; |
7 The method is:
4-Methylacetophenone (134 mg, 1.0 mmol), metal ruthenium complex [Cp*Ir(2,2'-bpyO)(OH)][Na] (4.6 mg, 0.01 mmol, 1 mol%) and water (1 mL) are added to 25 ml round bottom flasks. The air in the round bottom flask was replaced with hydrogen and the pressure of hydrogen gas in the system was 1 standard atmospheric pressure during the entire process of the reaction, and the reaction mixture was reacted at 30 °C, the hydrogen atmosphere was 12 h. After the reaction is completed, the solvent is removed by rotating, then the pure target compound is obtained by column chromatography (eluent: petroleum ether / ethyl acetate), yield: 91%. |
| 90% |
With sodium tetrahydridoborate In methanol Ambient temperature; |
|
| 90% |
With aluminum(III) oxide; sodium tetrahydridoborate In neat (no solvent) for 0.025h; Irradiation; |
|
| 90% |
With lithium amidotrihydridoborate In tetrahydrofuran at 20℃; for 1h; |
|
| 90% |
With sodium tetrahydridoborate In ethanol at 20℃; for 12h; |
|
| 90% |
With dodecane; Triethoxysilane; hydridoiron(II) (trimethylphosphane)3(benzophenone imine) In tetrahydrofuran at 55℃; for 4h; Schlenk technique; Inert atmosphere; |
|
| 90% |
With formic acid In lithium hydroxide monohydrate at 40℃; for 2h; Schlenk technique; Inert atmosphere; enantioselective reaction; |
|
| 90% |
With C46H60Fe2N4SSi; hydrogen In toluene at 50℃; for 20h; Autoclave; |
|
| 90% |
With [Cp*Ir(2,2'-bpyO)(OH)][Na]; hydrogen In lithium hydroxide monohydrate at 30℃; for 12h; Green chemistry; |
4.1. General procedure for catalytic hydrogenation of ketones,aldehydes or unsaturated aldehydes
General procedure: To an oven-dried 5 mL round-bottom flask were added ketonesor aldehydes or unsaturated aldehydes (1 mmol), cat. 6 (5.5 mg,1 mol %) and H2O (1 mL). Next, vacuum was applied to the flask followedby filling with H2 gas and keeping the flask attached to a balloonfilled with H2 gas. The mixture was heated at 30 °C for 12 h.After completion of the reaction, the mixture was extracted withethyl acetate (5 mL x 3). Then, the ethyl acetate layers were combined, dried with anhydrous sodium sulfate, filtered, and concentratedby evaporation under reduced pressure. The alcohols wereisolated and purified by filtering a hexanes/ethyl acetate (8:1)solution of the crude product through a pad of silica gel. Thenthe solvent was removed under reduced pressure to afford the correspondingproducts. The purity of alcohol products was assessedusing 1H NMR spectroscopy. |
| 89% |
With Zr(BH4)2Cl2(dabco)2 In lithium hydroxide monohydrate for 24h; Heating; |
|
| 89% |
With isopropanol; sodium hydroxide at 120 - 130℃; for 0.166667h; Microwave irradiation; |
|
| 89% |
With isopropanol; sodium hydroxide at 60℃; for 5h; Inert atmosphere; |
|
| 89% |
With C37H30Cl2N3OPRu; sodium isopropanolate; isopropanol for 0.166667h; Reflux; |
|
| 89% |
With [Cu(bathocuproine)(Xantphos)]PF6; [Co(trifluoromethanesulfonate)(1,4-di(picolyl)-7-(p-toluenesulfonyl)-1,4,7-triazacyclononane)](trifluoromethanesulfonate); lithium hydroxide monohydrate; triethylamine In acetonitrile at 30℃; for 5h; Irradiation; Inert atmosphere; |
|
| 89% |
With C15H20ClN3NiO2; isopropanol; potassium hydroxide at 100℃; for 12h; Inert atmosphere; Glovebox; |
|
| 89% |
With isopropanol; potassium hydroxide at 80℃; for 16h; Schlenk technique; |
|
| 89% |
With Rhodium trichloride; hydrogen In lithium hydroxide monohydrate at 100℃; for 10h; chemoselective reaction; |
|
| 88% |
Stage #1: para-methylacetophenone With (dppe)2Fe(H)2*(C7H8)2; Na-tetrakis(ethoxy)borate In toluene at 100℃; for 2h; visible light irradiation; Inert atmosphere;
Stage #2: With lithium hydroxide monohydrate; sodium hydroxide In methanol; toluene at 20℃; for 16h; |
|
| 88% |
With dichloro(p-cymene)ruthenium(II) dimer; dimethylamine borane In tetrahydrofuran at 70℃; for 24h; Inert atmosphere; Sealed ampoule; |
Representative procedure for metal-catalysed transfer hydrogenation
General procedure: To an oven dried, argon purged, ampoule containing [Ru(p-cymene)Cl2]2 (15.3 mg, 0.05 mmol, 2.5 mol%), substrate (1 mmol) and dry thf (to make a total of 3 mL), a solution of dimethylamine borane in thf was added. The ampoule was sealed and heated at 70 °C for 24 hours then cooled to room temperature; Method B - The reaction mixture was diluted with CH2Cl2 (50 mL), washed with water (2 x 25 mL), the organic layer was dried (MgSO4) and the solvents removed. To the residue hexane (100 mL was added, filtered and solvent concentrated in vacuo to afford the crude product. |
| 88% |
With C28H31ClN3Ru(1+)*F6P(1-); potassium-t-butoxide; isopropanol at 82℃; for 17h; Inert atmosphere; Green chemistry; |
|
| 88% |
With C26H30ClN3RhS(1+)*F6P(1-); potassium hydroxide In isopropanol at 80℃; for 3h; Schlenk technique; Inert atmosphere; |
|
| 88% |
With C22H21ClN3RuS2(1+)*F6P(1-); isopropanol; potassium hydroxide In acetonitrile at 80℃; for 3h; |
|
| 88% |
With propane-1,2,3-triol; potassium hydroxide at 20℃; for 3h; |
2.6. General procedure of reduction of aldehydes
General procedure: Aldehydes (1 mmol), KOH (2 mmol), catalyst 30 mg) were stirredin 3 mL of glycerol at room temperature for appropriate time.The progress of the reaction was monitored by TLC. The catalyst was separated magnetically and the product was extracted with ethyl acetate and the organic layer was evaporated in vacuum.The crude product thus obtained was purified by column chromatography on silica gel using n-hexane and ethyl acetate aseluent. |
| 88% |
With chloro(η6-p-cymene)(2-phenylbenzo[d]thiazole-κ-C,N)ruthenium(II); hydrogen In methanol; lithium hydroxide monohydrate at 80℃; for 3h; Inert atmosphere; Schlenk technique; Autoclave; |
|
| 88% |
With hydrogen In lithium hydroxide monohydrate at 150℃; for 6h; Autoclave; |
|
| 88% |
With potassium-t-butoxide; [(2,6-bis(phenylazo)pyridine)Ru(PMe2Ph)2(CH3CN)](ClO4)2; isopropanol at 82℃; for 6h; Inert atmosphere; |
|
| 88% |
With isopropanol at 150℃; for 24h; |
|
| 87% |
Stage #1: para-methylacetophenone With diphenylsilane In toluene at 20℃; for 48h;
Stage #2: With hydrogenchloride; methanol In toluene at 20℃; Further stages.; |
|
| 87% |
Stage #1: para-methylacetophenone With Triethoxysilane; diethylzinc(II); N,N-dimethyl-N'-(4-tert-butylphenyl)formamidine In tetrahydrofuran; hexane at 20 - 60℃; Inert atmosphere;
Stage #2: With sodium hydroxide In tetrahydrofuran; hexane; lithium hydroxide monohydrate at 0℃; for 1h; |
|
| 87% |
With formic acid; C25H26ClIrN2; anhydrous sodium formate In lithium hydroxide monohydrate at 80℃; for 12h; Inert atmosphere; |
|
| 87% |
With trans-RuCl(2-(2-pyridyl-6-ol)-1,10-phenanthroline)(PPh3)2PF6; potassium-t-butoxide; isopropanol at 80℃; for 0.5h; Inert atmosphere; Schlenk technique; |
|
| 87% |
With C9H8BrMnN2O3; potassium-t-butoxide In isopropanol at 20℃; for 0.333333h; Inert atmosphere; Schlenk technique; Glovebox; |
|
| 87.9% |
With C40H37ClN2PRuS(1+)*C24H20B(1-); isopropanol; potassium hydroxide at 82℃; for 2h; |
2.6. Typical procedure for transfer hydrogenation of ketones
General procedure: The mixture of a ketone (0.2 mmol) and base (0.08 mmol)containingthe catalyst (0.1 mol%) in 2-propanol (6 ml) was stirred at82 °C. After the reactionwas complete, diethyl ether could be addedto the mixture and extract the ruthenium complexes followed byfiltration and neutralized with 1N HCl, washed with water anddried over anhydrous Na2SO4. Conversion obtained is related to theresidual unreacted ketone. Percentage of conversionwas calculatedby using GC method of the crude mixture and compared with theauthentic samples. Acetone was identified as only by-product in allthe cases. As the catalyst is stable in all organic solvents and it canbe recovered and the work up process is also very simple for thiscatalytic system. |
| 87% |
With hydrogen; C27H27ClIrNO In methanol at 60℃; for 6h; Autoclave; |
|
| 86% |
With ammsnium formate In lithium hydroxide monohydrate; acetonitrile at 60℃; for 10h; Green chemistry; |
|
| 86% |
With Mn(CO)<SUB>3</SUB>Br(k<SUP>2</SUP>P,N-Ph<SUB>2</SUB>PN(H)Py); hydrogen; 1,1,1,3,3,3-hexamethyldisilazane potassium In toluene at 50℃; for 20h; Glovebox; Autoclave; Inert atmosphere; |
|
| 86% |
With sodium tetrahydridoborate In methanol at 20℃; |
|
| 86% |
With sodium tetrahydridoborate In methanol at 0 - 20℃; |
|
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