Application of lithium 4-methoxyaniline in catalysis of hydroboration reaction of imine and borane

Patent metadata

Field	Value
Publication number	US-11891408-B2
Application number	US-202117224378-A
Country	US
Kind code	B2
Filing date	Apr 7, 2021
Priority date	Oct 8, 2018
Publication date	Feb 6, 2024
Grant date	Feb 6, 2024

Abstract

The present invention relates to the application of lithium 4-methoxyaniline in catalysis of the hydroboration reaction of an imine and a borane. A catalyst, a borane and an imine are successively stirred and mixed until uniform, reacted for 1 to 2 hours, and then exposed to air so as to stop the reaction, and the reaction liquid is subjected to decompression to remove a solvent therein, so as to obtain a borate with different substituents. The lithium 4-methoxyaniline disclosed in the present invention can catalyze the hydroboration reaction of an imine and a borane in a high activity manner at room temperature, wherein the amount of the catalyst is merely 4-5 mol % of the molar amount of the imine, and the yield of the reaction can reach 90% or more. The yield of a borate with different substituents can reach 99% with mild reaction conditions under an optimized condition.

First claim

The invention claimed is:

1. A method of preparing a borate ester comprising:
reacting an imine with a borane in an organic solvent and in the presence of 4-methoxyaniline lithium as a catalyst at room temperature under anhydrous, oxygen-free, and inert gas conditions for 1-2 hours; and
stirring in air to stop reaction and to obtain the borate ester.

2. The method of claim 1 , wherein:
the imine has the following structure:

the borane is pinacol borane;
the borate ester has the following structure:

R 1 and R 2 are independently selected from the group consisting of halogen, methyl and methoxy.

3. The method of claim 1 , wherein the organic solvent is tetrahydrofuran.

4. The method of claim 1 , wherein an amount of 4-methoxyaniline lithium is 4% to 5% of a molar amount of the imine.

5. The method of claim 1 , wherein a molar ratio of the imine to the borane is 1:1 to 1:1.2.

6. The method of claim 5 , wherein the molar ratio of the imine to the borane is 1:1.2.

Assignees

• Univ Soochow

Inventors

• Xue Mingqiang
• Yan Dandan

Classifications

• C07F5/04 Primary

  Esters of boric acids · CPC title

• B01J31/12

  containing organo-metallic compounds or metal hydrides · CPC title

• C07F5/022 Primary

  without C-boron linkages · CPC title

• B01J2231/323

  Hydrometalation, e.g. bor-, alumin-, silyl-, zirconation or analoguous reactions like carbometalation, hydrocarbation · CPC title

• B01J31/0252

  with a metal-nitrogen link, e.g. metal amides, metal guanidides · CPC title