Application of deprotonated phenyl bridged beta-ketimine lithium compound in preparation of alcohol from ester

A technology of lithium ketimide and phenyl bridge is applied in the application field of preparing alcohol by hydroboration reaction. mild effect

Inactive Publication Date: 2020-10-13
SUZHOU UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0002] Existing hydroboration methods have significant disadvantages: LiAlH 4 and NaBH 4 The system security risk is very high, SmI 2 -H 2 O-Et 3 The N system needs a lot of reagents in excess, and the transition metal complex system needs to be carried out under high temperature and high pressure, and it needs to use a catalyst that is difficult to synthesize, and the cos

Method used

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  • Application of deprotonated phenyl bridged beta-ketimine lithium compound in preparation of alcohol from ester
  • Application of deprotonated phenyl bridged beta-ketimine lithium compound in preparation of alcohol from ester
  • Application of deprotonated phenyl bridged beta-ketimine lithium compound in preparation of alcohol from ester

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Under an inert gas atmosphere, 5.84 mg (0.005 mmol) of the catalyst was added to the reaction flask after dehydration and deoxygenation, and benzyl benzoate (94.9 μL, 0.5 mmol), pinacol borane (159.6 μL, 1.1mmol), THF (200 μL), at 60 o After reacting at C for 120 min, the reaction solution was exposed to air, and the solvent was removed under conventional reduced pressure to obtain the product boric acid ester, which was sampled and prepared for NMR, with mesitylene (69.6 μL, 0.5 mmol) as the internal standard, stirred evenly, and then added with dropwise Pipette a drop into the NMR tube, add CDCl 3 Dubbed into a solution, calculated 1 H spectrum yield was 96%. NMR data of the product: 1 HNMR (400 MHz, CDCl 3 ) δ 7.34 – 7.22 (m, 10H, ArH), 4.91 (s, 4H, OCH 2 ), 1.25 (s,24H, CH 3 ).

[0024] Add 1 g of silica gel and 2.5 mL of methanol to the system in which the solvent was removed after the hydroboration reaction, and react at 50°C for 2 hours. After the react...

Embodiment 2

[0030] Under an inert gas atmosphere, 5.84 mg of the catalyst was added to the reaction flask after dehydration and deoxygenation, methyl acetate (39.7 μL, 0.5 mmol), pinacol borane (159.6 μL, 1.1 mmol) were sequentially added with a pipette gun , THF (200μL), at 60 o After reacting at C for 120 min, the reaction solution was exposed to air, and the solvent was removed under conventional reduced pressure to obtain the product boric acid ester, which was sampled and prepared for NMR, with mesitylene (69.6 μL, 0.5 mmol) as the internal standard, stirred evenly, and then added with dropwise Pipette a drop into the NMR tube, add CDCl 3 Dubbed into a solution. Calculated 1 H spectrum yield was 95%. NMR data of the product: 1 H NMR (400 MHz, CDCl 3 ) δ 3.87 (q, J = 7.1 Hz, 2H, OCH 2 ), 1.22 (s, 24H, OBpin), 1.19 (t, J = 6.0Hz, 3H, CH 3 ).

[0031] Add 1 g of silica gel and 2.5 mL of methanol to the system in which the solvent was removed after the hydroboration reaction,...

Embodiment 3

[0033]Under an inert gas atmosphere, add 5.84 mg (0.005 mmol) of the catalyst to the reaction flask after dehydration and deoxygenation, and add methyl p-bromobenzoate (107.52 mg, 0.5 mmol) and pinacol borane successively with a pipette gun. (159.6 μL, 1.1 mmol), THF (200 μL), at 60 o After reacting at C for 120 min, the reaction solution was exposed to air, and the solvent was removed under conventional reduced pressure to obtain the product boric acid ester, which was sampled and prepared for NMR, with mesitylene (69.6 μL, 0.5 mmol) as the internal standard, stirred evenly, and then added with dropwise Pipette a drop into the NMR tube, add CDCl 3 Dubbed into a solution, calculated 1 H spectrum yield was 98%. NMR data of the product: 1 H NMR (400 MHz, CDCl 3 ) δ 7.40 (d, J = 8.3 Hz, 2H, ArCH), 7.17 (d, J = 8.2Hz, 2H, ArCH), 4.82 (s, 2H, OCH 2 ), 1.20 (s, 12H, OBpin), 1.19 (s, 12H, OBpin).

[0034] Add 1 g of silica gel and 2.5 mL of methanol to the system in which t...

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Abstract

The invention discloses application of a deprotonated phenyl bridged beta-ketimine lithium compound in the preparation of alcohol from ester. Ester and borane are used as raw materials, a hydroboration reaction is carried out; and after the hydroboration reaction is finished, silica gel and methanol are added, and a hydrolysis reaction is carried out to obtain alcohol. According to the applicationof the invention, the deprotonated phenyl bridged beta-ketimine lithium compound disclosed for the first time is used for catalyzing the hydroboration reaction of the ester and pinacol borane, so that a kind of efficient catalytic borohydride method is developed; the compound is simple in structure, easy to synthesize and capable of catalyzing the hydroboration reaction of the ester and borane with high activity. Compared with an existing catalytic system, the compound is easy to store, and particularly, exerts far smaller harm in use than an existing organic lithium reagent.

Description

technical field [0001] The invention relates to a lithium compound and its application in the field of organic synthesis, in particular to the application of a deprotonated β-ketimine lithium compound in the hydroboration reaction of esters to prepare alcohols. Background technique [0002] Existing hydroboration methods have significant disadvantages: LiAlH 4 and NaBH 4 The system security risk is very high, SmI 2 -H 2 O-Et 3 The N system needs a lot of reagents in excess, and the transition metal complex system needs to be carried out under high temperature and high pressure, and it needs to use a catalyst that is difficult to synthesize, and the cost is high. In recent years, the hydroboration reaction of esters has become one of the research hotspots of researchers. There are more and more reports on the hydroboration reaction of esters, mainly involving main group metal catalysts and rare earth metal catalysts. In 2014, Sadow's research group reported a Mg complex ...

Claims

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Application Information

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IPC IPC(8): C07C29/12C07C33/22C07F5/04B01J31/22
CPCB01J31/2243B01J2231/344B01J2531/11C07C29/12C07F5/04C07C33/22
Inventor 薛明强徐晓娟周帅康子晗洪玉标刘倩倩
Owner SUZHOU UNIV
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