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Alkyl-halide boron esterification reaction method free from transition metal catalysis

A technology of alkyl halides and alkyl borates, applied in the field of organic synthesis, can solve the problems of difficult handling, high cost, and complexity of the reaction, and achieve the effects of wide functional group compatibility and considerable yield

Active Publication Date: 2019-04-05
PEKING UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although these methods have been widely used, they still have obvious deficiencies in the following aspects: (1) the metal-ligand combination needs to be complex and rigorously screened, which is time-consuming and laborious; (2) due to the use of transition metal catalysts and strong bases, The reaction is usually very sensitive to air and moisture, and the cost is high; (3) stoichiometric Grignard reagent or organolithium reagent is required for Fe / Mn catalysis, and the reaction is not easy to handle

Method used

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  • Alkyl-halide boron esterification reaction method free from transition metal catalysis
  • Alkyl-halide boron esterification reaction method free from transition metal catalysis
  • Alkyl-halide boron esterification reaction method free from transition metal catalysis

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Experimental program
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Effect test

Embodiment 1

[0034] In the glove box, add t-BuOLi (0.75 mmol, 1.5 equivalents, 60.1 mg) to a vial equipped with a stirring bar, B 2 pin 2 (1.5mmol, 3 equivalents, 380.9mg), 0.85mL solvent methanol, 10 μL H 2 O, iodo-n-octane (0.5 mmol). The capped vial was removed from the glove box, and the reaction mixture was stirred at 50 °C for 48 hours. After cooling to room temperature, the reaction mixture was transferred to a 100 mL flask through methanol, and then a small amount of silica gel was added thereto. After the solvent was removed in vacuo, the residue was poured on a silica gel column, and purified by column chromatography. The developing solvent was a mixed solution of petroleum ether / ethyl acetate with a volume ratio of 50:1 to 30:1 to obtain the desired product. Octylboronic acid pinacol ester, yield 83%. The reaction was carried out in the same procedure using 0.5 mmol n-octane bromide, and the yield was 66%.

Embodiment 2

[0036] In the glove box, add t-BuOLi (1 mmol, 2 equivalents, 80.1 mg), B 2 (neop) 2 (Neopentyl glycol diboronate, 2mmol, 4 equivalents, 451.8mg), 0.85mL solvent methanol, 10 μL H 2 O, iodo-n-octane (0.5 mmol). The capped vial was removed from the glove box, and the reaction mixture was stirred at 50°C for 48 hours. After cooling to room temperature, the reaction mixture was transferred to a 100 mL flask through methanol, and then a small amount of silica gel was added thereto. After the solvent was removed in vacuo, the residue was poured on a silica gel column and purified by column chromatography. The developing solvent was a mixed solution of petroleum ether / ethyl acetate with a volume ratio of 30:1 to obtain the desired product n-octylboronic acid. Pentylene glycol ester, yield 67%.

Embodiment 3

[0038] In the glove box, add t-BuOLi (1 mmol, 2 equivalents, 80.1 mg), B 2 pin 2 (2mmol, 4 equivalents, 507.9mg), 0.85mL solvent methanol, 10 μL H 2 O, iodomethane (0.5 mmol). The capped vial was removed from the glove box, and the reaction mixture was stirred at 50 °C for 48 hours. After being cooled to room temperature, the reaction mixture was transferred to the test tube by methanol, a certain mass of internal standard n-decane was added, diluted with ethyl acetate, and the yield of the product methylboronic acid pinacol ester was measured by GC-fid method as 30%.

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Abstract

The invention discloses an alkyl-halide boron esterification reaction method free from transition metal catalysis. The method has the advantages that the transition metal catalysis is not needed, boric acid ester serves as a boron source, alkoxide serves as alkali, primary or secondary alkyl iodides or bromides are converted into the boric acid ester under mild conditions in an organic solvent anda small amount of water, high functional group compatibility is displayed, and the high yield is achieved. The obtained product, namely the boric acid ester, can be applied to important reactions inthe field of organic synthesis such as Suzuki coupling, thereby being converted into a series of compounds having application value.

Description

technical field [0001] The invention relates to the field of organic synthesis, in particular to a method for boron esterification of alkyl halides and biborates in an alkaline environment without transition metal catalysis, which can effectively convert carbon-halogen bonds into carbon-boron key. Background technique [0002] Organoboron compounds are important intermediates in synthesis. They can convert carbon-boron bonds into carbon-carbon and other chemical bonds by methods such as Suzuki coupling, which is of great significance in the field of organic synthesis. For alkyl borates, the traditional method is to use highly active reagents such as Grignard reagents or organolithium reagents as raw materials, but this type of method has obvious limitations in terms of functional group compatibility and regioselectivity. In this context, transition metal-catalyzed borylation of alkyl halides has become a general method for the synthesis of alkyl borates, including Cu, Ni, P...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07F5/04
CPCC07F5/04
Inventor 莫凡洋孙北奇刘谦益洪钧婷
Owner PEKING UNIV
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