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Selective ether bond breaking method of aryl alkyl ether

An aryl alkyl ether and selective technology, which is applied in the field of ether bond cleavage of aryl alkyl ethers, can solve problems such as insufficient demethylation chemical selectivity, and achieves low price, wide application range and chemical selectivity. improved effect

Active Publication Date: 2020-09-04
JINGCHU UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

These four methods can crack aryl alkyl ethers very well, especially the cleavage of some aryl alkyl ethers containing acid-labile functional groups can also react well, but for vanillic acid ester compounds , the chemoselectivity of demethylation is not good enough, and the ester group will also undergo non-hydrolytic cleavage to form 3,4-dihydroxybenzoic acid

Method used

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  • Selective ether bond breaking method of aryl alkyl ether
  • Selective ether bond breaking method of aryl alkyl ether
  • Selective ether bond breaking method of aryl alkyl ether

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Embodiment 1 (eugenol demethylation)

[0025]

[0026] In a 100ml round bottom flask, add acetonitrile (40ml), aluminum triiodide (2.242g, 5.5mmol) and N,N-dimethylformamide dimethyl acetal (0.894g, 7.5mmol), at 80 ℃ Stir for 15min, add eugenol (0.821g, 5mmol), continue to stir at 80°C for 18h, quench with 2M dilute hydrochloric acid (10ml) after the reaction is complete, then extract three times with ethyl acetate (50ml), combine the organic phases, first Wash with a saturated aqueous solution of sodium thiosulfate (10ml), then dry with anhydrous magnesium sulfate, filter, and the filtrate is desolvated with a rotary evaporator, and the residue is subjected to flash column chromatography (eluent is petroleum ether / ethyl acetate=4 : 1, volume ratio) purification to obtain 0.615g 4-allyl catechol (white solid, yield 82%).

[0027] R f =0.34 (petroleum ether / ethyl acetate=3:1), melting point 44-45°C.

[0028] 1 H NMR (400MHz, CDCl 3 )δ6.76(d, J=8.1Hz, 1H), 6.68(d,...

Embodiment 2

[0035] Embodiment 2 (eugenol demethylation)

[0036]

[0037] Add acetonitrile (40ml), aluminum triiodide (2.242g, 5.5mmol) and dimethyl carbonate (0.901g, 10mmol) into a 100ml round bottom flask, stir at 80°C for 15min, add eugenol (0.821g, 5mmol), continue to stir at 80°C for 18h, quench with 2M dilute hydrochloric acid (10ml) after the reaction is complete, then extract three times with ethyl acetate (50ml), combine the organic phases, and first use a saturated aqueous solution of sodium thiosulfate (10ml) Washing, then drying with anhydrous magnesium sulfate, filtering, the filtrate was removed with a rotary evaporator, and the residue was purified by flash column chromatography (eluent: petroleum ether / ethyl acetate=4:1, volume ratio) to obtain 0.667 g 4-allyl catechol (white solid, yield 88%).

Embodiment 3

[0038] Embodiment 3 (eugenol demethylation)

[0039]

[0040]Acetonitrile (40ml), aluminum triiodide (2.242g, 5.5mmol) and N-methylformamide dimethyl acetal (0.788g, 7.5mmol) were added to a 100ml round bottom flask, stirred at 80°C for 15min, Add eugenol (0.821g, 5mmol), continue stirring at 80°C for 18h, quench with 2M dilute hydrochloric acid (10ml) after completion of the reaction, then extract three times with ethyl acetate (50ml), combine the organic phases, and Wash with a saturated aqueous solution of sodium sulfate (10ml), dry over anhydrous magnesium sulfate, filter, remove the solvent from the filtrate with a rotary evaporator, and pass the residue through flash column chromatography (the eluent is petroleum ether / ethyl acetate=4:1, volume ratio) to obtain 0.595 g of 4-allyl catechol (white solid, yield 79%).

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Abstract

The invention discloses a selective aryl alkyl ether cracking method, which comprises that aryl alkyl ether, aluminum iodide and an additive are subjected to a selective ether bond cleavage reaction in an organic solvent at a temperature of -20 DEG C to a reflux temperature to generate phenol and derivatives thereof. The method is mild in condition and simple and convenient to operate, is suitablefor cracking aryl alkyl ether containing o-hydroxyl and o-carbonyl and acetal ether, and can also be used for removing tertiary carbon hydroxyl protecting groups with higher steric hindrance, such astriphenylmethyl, tertiary butyl and the like.

Description

technical field [0001] The invention relates to the technical field of intermediate synthesis of medicines and chemical raw materials, in particular to a selective ether bond breaking method of aryl alkyl ethers. Background technique [0002] Dealkylation of aryl alkyl ethers to prepare phenols or polyphenols through ether bond cleavage reactions is a widely used functional group transformation in pharmaceuticals and organic synthesis. Ether bond cleavage can usually be performed in HCl, HBr, HI, hydropyridine bromide, LiCl, BCl 3 、BBr 3 , TMSI, AlCl 3 and AlI 3 etc. under the action of Bronsted acid or Lewis acid. When the substrate contains acid- and base-sensitive functional groups or multiple reactive groups, it will be difficult to use these methods for selective ether bond cleavage. For example, demethylation of eugenol by these methods can only give moderate The low yield does not even obtain the product (Tetrahedron Letters 2014,55,2455). [0003] In order to s...

Claims

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Application Information

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IPC IPC(8): C07C39/19C07C37/055C07C67/31C07C69/84C07C69/732C07C39/08C07C39/24C07C45/64C07C47/565C07C49/825C07C49/248C07C47/575C07C49/84C07C253/30C07C255/53C07C39/28C07C41/26C07C43/23C07C269/06C07C271/28C07D309/12C07F7/18
CPCC07C37/055C07C67/31C07C45/64C07C253/30C07C41/26C07C269/06C07D309/12C07F7/1804C07F7/1892C07C39/19C07C69/84C07C69/732C07C39/08C07C39/245C07C47/565C07C49/825C07C49/248C07C47/575C07C49/84C07C255/53C07C39/28C07C43/23C07C271/28Y02P20/55
Inventor 田娟乐华鑫李义晋桑大永
Owner JINGCHU UNIV OF TECH
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