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A method for direct oxidation of benzylic c-h bond to ketone
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A benzylic and direct technology, applied in the field of direct oxidation of benzylic C-H bonds to ketones, can solve the problems of unstable peroxide oxidants, can not well achieve the selective oxidation of monoketones and diketones, and avoid metal residues. , Simple operation, high atomic economy effect
Active Publication Date: 2020-01-03
UNIV OF SCI & TECH OF CHINA
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Excessive unstable peroxide oxidizing agents cannot achieve selective oxidation of monoketones and diketones
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Embodiment 1
[0020] p-Methoxyacetophenone Synthesis
[0021] Add 0.5 equivalent of NHPI to a 25 mL Schlenk reaction tube, dry in vacuum for 15 minutes, cover with an oxygen bulb, add 1 mL of acetonitrile, 1.0 equivalent of tert-butyl nitrite, and 0.5 mmol of p-ethylanisole in sequence under an oxygen atmosphere. Put a polytetrafluoro stopper on the tube and put it in an oil bath, and react at 80°C for 24h. After the reaction was completed, the solvent was concentrated under reduced pressure to remove acetonitrile, and separated by column chromatography, and the eluent was petroleumether / ethyl acetate (v:v=20:1) to obtain p-methoxyacetophenone. Yield 83%, pale yellow solid; 1 H NMR (CDCl 3 ,400MHz): δ7.92(d,J=9.2Hz,2H),6.92(d,J=8.8Hz,2H),3.85(s,3H),2.54(s,3H); 13 C NMR (CDCl 3 ,100MHz): δ196.7,163.4,130.5,130.3,113.6,55.4,26.3.
Embodiment 2
[0023] 4-Acetoxyacetophenone Synthesis
[0024]Add 1.0 equivalent of NHPI to a 25 mL Schlenk reaction tube, dry in vacuum for 15 minutes, cover with an oxygen bulb, add 1 mL of acetonitrile, 2.0 equivalents of tert-butyl nitrite, and 0.5 mmol of p-acetoxyethylbenzene in an oxygen atmosphere. Put a polytetrafluoro stopper on the reaction tube and put it in an oil bath, and react at 80°C for 24h. After the reaction was completed, the solvent was concentrated under reduced pressure to remove acetonitrile, and separated by column chromatography, the eluent was petroleumether / ethyl acetate (v:v=10:1) to obtain 4-acetoxyacetophenone. Yield 72%, white solid; 1 H NMR (CDCl 3 ,400MHz): δ7.96(d,J=6.8Hz,2H),7.16(d,J=6.8Hz,2H),2.56(s,3H),2.30(s,3H); 13 C NMR (CDCl 3 ,100MHz): δ196.8, 168.8, 154.2, 134.5, 129.8, 121.7, 26.5, 21.0.
Embodiment 3
[0026] p-Fluoroacetophenone Synthesis
[0027] Add 0.5 equivalent of NHPI to a 25 mL Schlenk reaction tube, dry in vacuum for 15 minutes, cover with an oxygen bulb, add 1 mL of acetonitrile, 1.0 equivalent of tert-butyl nitrite, and 0.5 mmol of p-fluoroethylbenzene in the reaction tube After adding a polytetrafluoro stopper, put it into an oil bath, and react at 80°C for 24h. After the reaction was completed, the solvent was concentrated under reduced pressure to remove acetonitrile, and separated by column chromatography, and the eluent was petroleum ether / ethyl acetate (v:v=50:1) to obtain p-fluoroacetophenone. Yield 78%, pale yellow oil; 1 HNMR (CDCl 3 ,400MHz):δ7.96(dd,J=8.2Hz,5.4Hz,2H),7.10(t,J=8.4Hz,2H),2.56(s,3H); 13 C NMR (CDCl 3 ,100MHz): δ196.4,166.9,164.4,133.5(d,J=3.0Hz),130.8(d,J=9.8Hz),115.6(d,J=21.9Hz),26.4.
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Abstract
The invention discloses a method for directly oxidizing a benzyl-position C-H bond into ketone, wherein aryl ethyl compounds are catalyzed and oxidized by nitrite ester; a synergistic catalytic system of free radical initiator and nitrite ester is adopted, and a catalytic system of non-metallic catalyst and oxygen is adopted, the oxidization of the C-H bond of a free radical-activated arylside chain is simple in operation; after completing the reaction, petroleumether / ethyl acetate at a volume ratio of (50-1):1 is used as an eluent; column chromatography separation is performed to obtain a target product. The catalytic system in the invention uses oxygen as an oxygen source and has high atomic economy; the invention is a non-metallic catalytic system and provides a novel method for avoid metal residues in synthetic drugs; for diethyl aromatic hydrocarbon, the method provided by the invention can be adopted to selectively oxidize diethyl aromatic hydrocarbon into monoketone and diketone; the method of the invention can be adopted to efficiently synthesize tranquillizer lenperone, so that a novel method for synthesizing lenperone is provided.
Description
technical field [0001] The invention belongs to catalytic benzyl position containing CH 2 The technical field of synthesizing ketone compounds from aromatic hydrocarbon compounds, specifically relates to a method for directly oxidizing arylside chain C-H bonds into ketones. Background technique [0002] Acyl groups are ubiquitous in organic synthesis intermediates and pharmaceutical compounds, so the direct oxidation of aryl side chain C-H bonds to ketones has been widely used in chemical industry, especially in pharmaceutical fields. The traditional method of directly oxidizing the C-H bond of the aryl side chain to ketone is to make potassiumpermanganate or potassium dichromate under harsh conditions, and there are many by-products, and the oxidation cannot be selectively controlled when there are two side chains. . In recent years, the use of transition metals as catalysts has been developed. Due to the high cost of transition metal complex oxidants and metal residues...
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