Method for preparing cyclopentene/cyclohexene-1-boronic acid pinacol ester

A technology of pinacol ester and cyclohexene, which is applied in the field of organic chemical synthesis, can solve the problems of high raw material cost, many impurities, and low yield, and achieve the effects of reduced raw material cost, easy reaction conditions, and simple process operation

Inactive Publication Date: 2013-04-17
DALIAN NETCHEM CHIRAL TECH
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Problems solved by technology

Currently known cyclopentene / hexene-1-boronic acid pinacol ester synthesis methods all adopt cyclopentanone / cyclohexanone and equivalent p-toluenesulfonyl hydrazide, reflux in ethanol, and filter to obtain Cyclopentyl / cyclohexyl p-toluenesulfonylhydrazone; 4eq n-butyl is added dropwise to 1eq cyclopentyl / cyclohexyl p-toluenesulfonylhydrazone and 5eqTMEDA at -45℃~-60℃, Raise to room temperature, after the reaction of the raw materials is completed, lower the temperature to -70°C, add isopropoxy borate pinacol ester dropwise, and keep the temperature between -60°C and -70°C, and stir for 2 hours after dropping , naturally raised to room temperature, quenched, extracted and distilled to obtain the product, but this method has many defects: (1) The reaction requires ultra-low temperature, the industrial scale-up operation is cumbersome, and the refrigeration cost is increased; (2) The selectivity of the reaction is very poor and there are many impurities , the yield is low during vacuum distillation; (3) 4eq butyllithium is used in the literature, and pinacol isopropoxy borate needs to be self-made, the cost of raw materials is high and there are safety hazards in operation

Method used

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  • Method for preparing cyclopentene/cyclohexene-1-boronic acid pinacol ester
  • Method for preparing cyclopentene/cyclohexene-1-boronic acid pinacol ester

Examples

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example 1

[0023] A method for preparing cyclohexene-1-boronic acid pinacol ester, with PdCl 2 As catalyst, with tricyclohexylphosphine (2) as ligand:

[0024] The preparation of the first step raw material 1-chlorocyclohexene:

[0025] Add 320.30 g (1.556 mol) of phosphorus pentachloride and 800 g of n-heptane into a 2L four-necked flask equipped with a magnetic stirrer, a thermometer, a condenser tube and a tail gas lye absorption device, raise the temperature to 70°C to 74°C, drop Add a mixed solution of 150g (1.533mol) cyclohexanone and 100g n-heptane, drop it for about 2 hours, continue to react for half an hour, after cooling down to 0°C, add 1L of 2mol / L sodium hydroxide solution dropwise, and stir for 1 hour , separated the upper organic layer, dried over anhydrous magnesium sulfate, rectified under reduced pressure, collected the middle distillate at 34-36°C, and obtained 148.09g of 1-chlorocyclohexene, with a GC purity of 97.9% and a yield of 82.2%;

[0026] The preparation o...

Embodiment 2

[0029] A kind of method for preparing cyclopentene-1-boronic acid pinacol ester, with PdCl 2 As a catalyst, with 2-dicyclohexylphosphine-2 ， -(N,N-Dimethylamino)biphenyl (5) as ligand:

[0030] The preparation of the first step raw material 1-chlorocyclopentene:

[0031] Add 374.18.30 g (1.818 mol) of phosphorus pentachloride and 803 g of n-heptane into a 2L four-necked flask equipped with a magnetic stirrer, thermometer, condenser and tail gas alkali absorption device, and heat up to 70°C to 74°C , add dropwise a mixed solution of 151.41g (1.803mol) cyclopentanone and 102g n-heptane, drop it in about 2 hours, continue to react for half an hour, after cooling down to 0°C, add dropwise 1L of 2mol / L sodium hydroxide solution, Stir for 1 hour, separate the upper organic layer, dry over anhydrous magnesium sulfate, and distill under reduced pressure to obtain 149.11 g of 1-chlorocyclopentene with a GC purity of 97.2% and a yield of 81.1%;

[0032] The preparation of second step...

Embodiment 3

[0035] A kind of method for preparing cyclopentene-1-boronic acid pinacol ester, with PdCl 2 As a catalyst, with 2-dicyclohexylphosphine-2 ， , 4 ， ,6 ， - Triisopropylbiphenyl (3) as ligand:

[0036] The preparation of the first step raw material 1-chlorocyclopentene:

[0037] Same as step 1 of example 2

[0038] The preparation of second step cyclopentene-1-boronic acid-pinacol ester:

[0039]Add 149.21 g (1.463 mol) of 1-chlorocyclohexene, 2.57 g (0.0146 mol) of palladium chloride, and the ligand ( 3) 10.1g (0.0292mol), double pinacol borate 382.02g (1.504mol), potassium acetate 440.13g (4.49mol), toluene 1L, heated to 110°C, refluxed for 12h, controlled by GC, the reaction ended Finally, the reaction solution was filtered with 10 g of diatomaceous earth as the main filter aid, and the filter cake was discarded. The organic layer was washed twice with 400 mL of water (200×2), and dried with 10 g of anhydrous magnesium sulfate for 4 h. The desiccant was filtered off, t...

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Abstract

The invention discloses a method for preparing cyclopentene/cyclohexene-1-boronic acid pinacol ester. The method comprises the step of carrying out coupling reaction on 1-chlorine-cyclopentene/cyclohexene serving as a raw material in an organic solvent A in the presence of monophosphate ligand and a palladium catalyst based on potassium acetate as alkali so as to prepare the cyclopentene/cyclohexene-1-boronic acid pinacol ester. The method is characterized in that the physicochemical reaction at the n-butyllithium and ultralow temperature condition in the literature is avoided, and the palladium catalyst is adopted for catalyzing, so that the amount of the used catalyst is reduced, and the cyclopentene/cyclohexene-1-boronic acid pinacol ester can be prepared in relatively high yield at the acceptable temperature; the boronizing agent n-butyllithium/isopropoxy boronic acid pinacol ester system is replaced by the boronizing agent palladium catalyst/bis(pinacolato)diboron system, and therefore, the cost of the raw materials is greatly reduced, the reaction condition is relatively easy to realize, amplification is easy, and the technical operation is simpler and more convenient.

Description

technical field [0001] The invention relates to the technical field of organic chemical synthesis, in particular to a method for preparing cyclopentene / cyclohexene-1-boronic acid pinacol ester. Background technique [0002] Compared with highly reactive bromoalkenes and iodoalkenes, chlorinated alkenes are cheap and easy to obtain, but the application of chlorinated alkenes in organic synthesis is limited due to the low reactivity of chlorine atoms. Since the 1990s, transition metal-catalyzed coupling reactions, especially palladium-catalyzed coupling reactions, have been widely used in various fields of organic synthesis. By properly modifying palladium catalysts or selecting appropriate ligands, highly active palladium Catalyst, can realize the coupling reaction of chlorinated alkenes. Currently known cyclopentene / hexene-1-boronic acid pinacol ester synthesis methods all adopt cyclopentanone / cyclohexanone and equivalent p-toluenesulfonyl hydrazide, reflux in ethanol, and ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07F5/02
Inventor 于双安昌辉王丽杰
Owner DALIAN NETCHEM CHIRAL TECH
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