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Process for the dehalogenation of thiochroman and dihydrobenzothiophene derivatives

A technology of compounds and general formulas, applied in botany equipment and methods, organic chemical methods, biocides, etc., can solve problems such as unsatisfactory product yield and quality

Inactive Publication Date: 2001-08-29
AMERICAN CYANAMID CO +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Also, product yield and quality may be less than satisfactory

Method used

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  • Process for the dehalogenation of thiochroman and dihydrobenzothiophene derivatives

Examples

Experimental program
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Effect test

Embodiment 1

[0018] 1,1-dioxide-4-(O-methoxyxime)-2,3-dihydro-5-methyl-4-oxo-4H-1-benzothiopyran-6-carboxylic acid ethyl Preparation of esters

[0019] 1,1-dioxide-4-(O-methoxime)-8-chloro-2,3-dihydro-5-methyl-4-oxo-4H-1-benzothiopyran-6-carboxy A stirred mixture of ethyl acetate (800 g, 2.31 mol) in ethanol was treated with ammonium formate (729.4 g, 11.57 mol) and 10% Pd / C (50% water) (800 g, 0.375 mol) and heated to reflux for 1 hour temperature, maintained at reflux for approximately 4 hours (until completion by HPLC analysis), stirred at room temperature for 19 hours and filtered through a bed of celite. The filter cake was slurried in tetrahydrofuran (THF) and filtered several times. All filtrates were combined, concentrated to about 1 / 3 of the original volume and filtered through a bed of celite. The filter cake was washed with additional THF. The filtrates were combined, designated Filtrate A and set aside.

[0020] Repeat the above steps with the same amount of reactants. ...

Embodiment 2

[0022] Preparation of ethyl 1,1-dioxide-2,3-dihydro-3,3,4-trimethylbenzo[b]thiophene-5-carboxylate

[0023] Using ethyl 1,1-dioxide-7-chloro-2,3-dihydro-3,3,4-trimethylbenzo[b]thiophene-5-carboxylate as starting material, and according to Example 1 Essentially the same procedure as described in gives the title product, using 1 Confirmed by HNMR, IR and mass spectral analysis.

Embodiment 3

[0025] Preparation of 1,1-dioxide-2,3-dihydro-3,3,4-trimethylbenzo[b]thiophene-5-carboxylic acid

[0026] Under nitrogen, 1,1-dioxide-7-chloro-2,3-dihydro-3,3,4-trimethylbenzo[b]thiophene-5-carboxylic acid (1.0g, 3.46mmol), A mixture of ammonium formate (1.0 g, 15.9 mmol) in ethanol was treated with 10% Pd / C (50% water) (0.50 g, 0.235 mmol Pd), heated at reflux temperature for 1 hour (reaction proved complete by HPLC analysis), cooled to room temperature and filtered through celite. The filter cake was washed with ethanol. The combined filtrates were concentrated in vacuo to give a residue. The residue was taken up in aqueous NaOH, cooled to 5°C and acidified to pH 1 with concentrated HCl to give a precipitate. Filter the mixture. The filter cake was washed with water and air dried to afford 0.80 g (91% yield) of the title product as a white solid with a purity of 99.3% by HPLC analysis, using 1 Confirmed by HNMR.

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Abstract

There is provided a process for the dehalogenation of a compound of formula II via the use of a transition metal catalyst and ammonium formate at atmospheric pressure.

Description

Background of the invention [0001] Thiopan and thiophene herbicides and methods for their preparation are described in, among other publications, US Patent 5,506,194, US Patent 5,607,898 and WO 97 / 08164. 6-(arylcarbonyl)thiochroman and 5-(arylcarbonyl)benzothiophene derivatives are effective herbicides at low application rates on economically important crops such as corn and rice Selective control of noxious weeds in the presence of [0002] The usual route to these useful herbicides entails the dehalogenation of 8-halo-6-carboethoxythiochroman or 7-halo-5-carboethoxythiochroman intermediate compounds. To date, the dehalogenation process of such intermediate compounds has required high pressure hydrogenation techniques. Also, product yield and quality may be less than satisfactory. Since the dehalogenated 6-carboethoxythiochrome and 5-carboethoxythiochrome intermediates (especially as important intermediates in the production of thiophenes) and alternative and efficient me...

Claims

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Application Information

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IPC IPC(8): A01N43/18C07B61/00C07D333/54C07D335/06C07D409/06
CPCC07D335/06C07D409/06C07D333/54C07D333/68
Inventor T·W·小德拉伯
Owner AMERICAN CYANAMID CO
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