Method for preparing boric acid ester using uncatalyzed hydroboration of carboxylic acid

Patent metadata

Field	Value
Publication number	US-2022017543-A1
Application number	US-201917311314-A
Country	US
Kind code	A1
Filing date	Mar 7, 2019
Priority date	Dec 6, 2018
Publication date	Jan 20, 2022
Grant date	—

Abstract

Disclosed is a method for preparing a boric acid ester using non-catalyzed hydroboration of a carboxylic acid. The method includes: in an inert gas atmosphere, mixing pinacolborane and a carboxylic acid and stirring until uniform in a reaction flask subjected to dehydration and deoxygenation treatments, reacting for 6-12 hours to obtain the boric acid ester, then adding silica gel and methanol, and conducting a hydrolysis reaction to prepare an alcohol compound. The carboxylic acid is acetic acid, caproic acid, pentanoic acid, heptanoic acid, trimethylacetic acid, adipic acid, benzoic acid, 4-bromobenzoic acid, 4-fluorobenzoic acid, 1-naphthoic acid, 2-methoxybenzoic acid, 4-tert-butylbenzoic acid, 4-ethoxybenzoic acid, 2-bromobenzoic acid, 4-iodobenzoic acid, 3-phenylpropionic acid, diphenyl acetic acid, 2-phenylbutyric acid, indole-3-acetic acid, o-carboxyl phenylacetic acid or 2-methyl-5-bromobenzoic acid. The present invention utilizes a carboxylic acid to efficiently undergo hydroboration with borane without a catalyst for the first time.

First claim

1 . A method for preparing a borate ester by non-catalytic hydroboration of a carboxylic acid, comprising the following steps: without a solvent and a catalyst, conducting a non-catalytic hydroboration of the carboxylic acid and a borane to prepare the borate ester.

2 . The method according to claim 1 , wherein the borane is pinacolborane; and the carboxylic acid is acetic acid, caproic acid, valeric acid, heptanoic acid, trimethylacetic acid, adipic acid, benzoic acid, 4-bromo-benzoic acid, 4-fluorobenzoic acid, 1-naphthoic acid, 2-methoxybenzoic acid, 4-tert-butylbenzoic acid, 4-ethyl oxybenzoic acid, 2-bromobenzoic acid, 4-iodobenzoic acid, 3-phenylpropionic acid, diphenylacetic acid, 2-phenylbutyric acid, indole-3-acetic acid, o-carboxyphenylacetic acid, or 2-methyl-5-bromobenzoic acid.

3 . The method according to claim 1 , wherein a molar ratio of the carboxylic acid and borane is from 1:3 to 1:7; and the hydroboration is carried at room temperature for 6 to 12 hours.

4 . The method according to claim 1 , wherein the hydroboration is carried out under the inert gas atmosphere; and the hydroboration is stopped by contacting air to obtain the borate ester.

5 . A method for preparing an alcohol compound from a carboxylic acid, comprising the following steps: without a solvent and a catalyst, conducting a non-catalytic hydroboration of the carboxylic acid and a borane; after the hydroboration, adding silica gel and methanol, conducting a hydrolysis reaction to prepare the alcohol compound.

6 . The method according to claim 5 , wherein a molar ratio of the carboxylic acid and borane is from 1:3 to 1:7; the borane is pinacolborane; and the carboxylic acid is acetic acid, caproic acid, valeric acid, heptanoic acid, trimethylacetic acid, adipic acid, benzoic acid, 4-bromobenzoic acid, 4-fluorobenzoic acid, 1-naphthoic acid, 2-methoxybenzene Formic acid, 4-tert-butylbenzoic acid, 4-ethoxybenzoic acid, 2-bromobenzoic acid, 4-iodobenzoic acid, 3-phenylpropionic acid, diphenylacetic acid, 2-phenylbutyric acid, indole-3-acetic acid, o-carboxyphenylacetic acid, or 2-methyl-5-bromobenzoic acid.

7 . The method according to claim 5 , wherein the hydroboration is carried at room temperature for 6 to 12 hours; and the hydrolysis reaction is conducted at 50° C. for 3 h.

8 . The method according to claim 5 , wherein the hydroboration is under the inert gas atmosphere; the hydroboration is stopped by contacting air, and silica gel and methanol are added to conduct the hydrolysis reaction to prepare the alcohol compound.

9 . An application of a carboxylic acid and a borane in preparing a borate ester, wherein the application is carried out without a catalyst; the borane is pinacolborane; and the carboxylic acid is acetic acid, caproic acid, valeric acid, heptanoic acid, trimethylacetic acid, adipic acid, benzoic acid, 4-bromobenzoic acid, 4-fluorobenzoic acid, 1-naphthoic acid, 2-methoxybenzoic acid, 4-tert-butyl benzoic acid, 4-ethoxybenzoic acid, 2-bromobenzoic acid, 4-iodobenzoic acid, 3-phenylpropionic acid, diphenylacetic acid, 2-phenylbutyric acid, indole-3-acetic acid, o-carboxyphenylacetic acid or 2-methyl-5-bromobenzoic acid.

10 . The application according to claim 9 , wherein a molar ratio of the carboxylic acid and the borane is from 1:3 to 1:7.

Assignees

• Univ Soochow

Inventors

• Xue Mingqiang
• Xu Xiaojuan
• Yan Dandan

Classifications

• C07F5/04 Primary

  Esters of boric acids · CPC title

• C07B41/02 Primary

  of hydroxy or O-metal groups · CPC title

• C07C2602/08

  the other ring being five-membered, e.g. indane · CPC title

• C07C41/26

  by introduction of hydroxy or O-metal groups · CPC title

• C07C29/09

  by hydrolysis · CPC title