Organic compounds -- part of the class 532-570 series – Organic compounds – Nitrogen attached directly or indirectly to the purine ring...
Patent
1996-08-13
1998-07-28
Grumbling, Matthew V.
Organic compounds -- part of the class 532-570 series
Organic compounds
Nitrogen attached directly or indirectly to the purine ring...
C07D24136
Patent
active
057864799
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process for producing a 6-substituted 2(1H)-quinoxalinone.
The 6-substituted 2(1H)-quinoxalinone is useful as an intermediate for an excellent herbicide, as disclosed in Japanese Examined Patent Publication No. 33389/1985.
BACKGROUND ART
As a method for producing a 6-substituted 2(1H)-quinoxalinone, it is common to produce it by reducing the corresponding 6-substituted 2(1H)-quinoxalinone-N-oxide.
A reagent reduction method wherein zinc metal, sodium borohydride, a sulfite compound or the like is used as a reducing agent, or a hydrogen reduction method wherein a palladium catalyst, a platinum catalyst, a Raney nickel catalyst or the like is used, has been known.
In the hydrogen reduction method wherein a catalyst is used, a reaction for removal of the substituent may occur depending upon the type of the substituent of the 6-substituted 2(1H)-quinoxalinone. As such a substituent, a halogen atom or the like may, for example, be mentioned.
To prevent such a reaction for removal of the substituent, a method has been developed wherein hydrogen reduction is carried out in the presence of a palladium catalyst, a platinum catalyst, a Raney nickel catalyst or the like which is poisoned with a sulfur compound.
In the reagent reduction method, the yield is poor with a reduction method wherein zinc metal is used.
With a reduction method wherein sodium borohydride is used, the yield is high, and the reaction operation is relatively easy, but in addition to a drawback that the cost is high, it may often happens that a reduced product having the reaction proceeded excessively is produced as a by-product.
A reduction method wherein a sulfite compound is used, is inexpensive, but a 2,3-dihydroxyquinoxaline compound will be produced as a by-product, whereby the yield will be poor.
For the method wherein hydrogen reduction is carried out in the presence of a palladium catalyst, a platinum catalyst or a Raney nickel catalyst poisoned with a sulfur compound, a high level of technique is required for the preparation of the catalyst, and it may often happen that the reduction rate decreases, or the reaction for removal of the substituent will not be suppressed.
Further, hydrogen reduction of a slurry system having an alkali salt of the 6-substituted 2(1H)-quinoxalinone-N-oxide precipitated, by means of the above catalyst, is difficult, and in order to let the hydrogen reduction proceed, it is necessary to dissolve the alkali salt of the 6-substituted 2(1H)-quinoxalinone-N-oxide.
DISCLOSURE OF THE INVENTION
The present inventors have made an extensive study to overcome the drawbacks of the above reduction reaction and as a result, have found that the conversion and selectivity can be improved to a large extent by a reduction reaction wherein an inexpensive alkali metal hydrosulfide and/or alkali metal sulfide is used. The present invention has been accomplished on the basis of this discovery.
Namely, the present invention provides a process for producing a 6-substituted 2(1H)-quinoxalinone of the formula (I): ##STR3## wherein X is a halogen atom, a trihalogeno-substituted C.sub.1-5 alkyl group or a nitro group, which comprises reacting a 6-substituted 2(1H)-quinoxalinone-N-oxide of the formula (II): ##STR4## wherein X is a halogen atom, a trihalogeno-substituted C.sub.1-5 alkyl group or a nitro group, with an alkali metal hydrosulfide and/or an alkali metal sulfide in the presence of from 1 to 20 mol times of an alkali;
the process for producing a 6-substituted 2(1H)-quinoxalinone of the formula (I), wherein after reacting the 6-substituted 2(1H)-quinoxalinone-N-oxide of the formula (II) with an alkali metal hydrosulfide and/or an alkali metal sulfide in the presence of from 1 to 20 mol times of an alkali, the reaction product is added to and treated with an acid of from 80.degree. to 100.degree. C.;
the process for producing a 6-substituted 2(1H)-quinoxalinone of the formula (I), wherein a 4-halogeno-2-nitroacetoacetoanilide of the formula (III): ##STR5## is reacted in th
REFERENCES:
Chemical Abstracts, vol. 104, No. 28, pp. 665-666, JP 60 158 184, 1986; Aug. 19, 1985.
Chemical Abstracts, vol. 98, No. 98, p. 661, 1983, JP 57 197 270, Dec. 3,1982.
Hashiba Isao
Hatanaka Masataka
Bucknum Michael
Grumbling Matthew V.
Nissan Chemical Industries Ltd.
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