Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Reexamination Certificate
2000-07-06
2001-04-17
O'Sullivan, Peter (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
C560S030000, C564S099000, C564S176000, C564S218000
Reexamination Certificate
active
06218565
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The invention relates to a novel process for preparing N-(3-amino-4-fluoro-phenyl)-sulphonamides, N-(3-amino-4-fluoro-phenyl)-carboxamides and N-(3-amino-4-fluoro-phenyl)-carbamates which can be used as intermediates for preparing herbicidally active compounds.
BACKGROUND OF THE INVENTION
It is known that N-(3-amino-4-fluoro-phenyl)-sulphonamides are obtained when corresponding N-(3-nitro-4-fluoro-phenyl)-sulphonamides are reacted with reducing or hydrogenating agents, such as, for example, iron in the presence of an acid, such as, for example, acetic acid, or hydrogen in the presence of a catalyst, such as, for example, platinum oxide (cf. EP-A-496595). However, the preparation of the required starting materials by selective reduction of 1-fluoro-2,4-dinitro-benzene and subsequent reaction with sulphonyl chlorides involves technical problems. In particular attempts to hydrogenate 1-fluoro-2,4-dinitro-benzene selectively to 1-fluoro-4-amino-2-nitro-benzene always yield mixtures of the possible monohydrogenated products and the dihydrogenated product. For this reason, 1-fluoro-4-amino-2-nitro-benzene (cf. EP-A-127079; Recueil Trav. Chim. Pays-Bas 65 (1946), 329) (and also 1-fluoro-2,4-diamino-benzene (cf. Bull. Soc. Chim. Fr 132 (1995), 306-313)) are generally prepared by reduction with metals or with metal compounds, such as, for example, with iron in the presence of iron(II) sulphate or in the presence of acetic acid, or with tin(II) chloride in the presence of hydrochloric acid. However, the use of such reducing agents in industry should be avoided, if possible, owing to the associated disposal problems.
Furthermore, it is known that N-(3-amino-4-chloro-phenyl)-sulphonamides and N-(3-amino-4-chloro-phenyl)-carboxamides are obtained when 1-chloro-2,4-diamino-benzene is reacted with sulphonyl chlorides and carbonyl chlorides, respectively (cf. WO-A-9727171). However, the yields and quality of the products in these reactions are not always entirely satisfactory. Since chlorine and fluorine as substituents on arenes frequently have a very different directing effect for further reactions, an analogous reaction of 1-fluoro-2,4-diamino-benzene with sulphonyl chlorides or carbonyl chlorides could furthermore not be expected to be a matter of course.
DETAILED DESCRIPTION OF THE INVENTION
It has now been found that N-(3-amino-4-fluoro-phenyl)-sulphonamides, N-(3-amino-4-fluoro-phenyl)-carboxamides and N-(3-amino-4-fluoro-phenyl)-carbamates of the general formula (I)
in which
A represents SO
2
, CO or CO
2
and
R represents in each case optionally substituted alkyl or aryl
are obtained in very good yields and in high purity when
1-fluoro-2,4-diamino-benzene of the formula (II)
or an acid adduct thereof
is reacted with sulphonyl chlorides, carbonyl chlorides or chloroformic esters of the general formula (III)
in which
A and R are as defined above
in the presence of an acid acceptor and in the presence of a diluent at temperatures between −20° C. and +100° C.
Surprisingly, it is possible to obtain N-(3-amino-4-fluoro-phenyl)-sulphonamides, N-(3-amino-4-fluoro-phenyl)-carboxamides and N-(3-amino-4-fluoro-phenyl)-carba-mates of the general formula (I) in very good yields and in high purity by the process according to the invention, although the formation of approximately equimolar mixtures of the possible “simple” sulphonylation products or acylation products—possibly also contaminated to a relatively large extent by products of multiple sulphonylation or acylation—was to be expected.
It is an advantage of the process according to the invention that the starting material-1-fluoro-2,4-diamino-benzene—can be obtained very easily in one step by catalytic hydrogenation from 1-fluoro-2,4-dinitro-benzene, so that, in contrast to the prior art (cf. EP-A-496595), a further reduction step is no longer required.
A further advantage of the process according to the invention is that the reaction does not have to be carried out in a mixture of different solvents (cf. WO-A-9727171), but that one solvent is sufficient.
Furthermore, it is particularly advantageous that the reaction products of the general formula (I) can in many cases be employed without isolation, i.e. in the reaction mixture of the reaction according to the invention, directly for further conversions, such as, for example, acylations or sulphonylations (with carbonyl chlorides, chloroformic esters, sulphonyl chlorides, etc.), which give pure products in good yields.
The process according to the invention is therefore a useful advance on the prior art.
Using, for example, 1-fluoro-2,4-diamino-benzene and methanesulphonyl chloride as starting materials, the course of the reaction in the process according to the invention can be illustrated by the following formula scheme:
The compound 1-fluoro-2,4-diamino-benzene of the formula (II) to be used as starting material in the process according to the invention is already known (cf. Bull. Soc. Chim. Fr. 132 (1995), 306-313).
The compound of the formula (II) can advantageously be prepared by catalytic hydrogenation of 1-fluoro-2,4-dinitro-benzene.
Suitable for use as acid adducts of the compound of the formula (II) are in particular salts with strong acids, such as hydrochloric acid or sulphuric acid. The mono- and bis-hydrochlorides may be mentioned as being preferred. The formula (III) provides a general definition of the sulphonyl chlorides, carbonyl chlorides and chloroformic esters further to be used as starting materials in the [lacuna] according to the invention. In the formula (III)
A preferably represents SO
2
, CO or CO
2
and
R preferably represents optionally cyano-, halogen- or C
1
-C
4
-alkoxy-substituted alkyl having 1 to 6 carbon atoms or preferably represents optionally cyano-, nitro-, halogen-, C
1
-C
4
-alkyl-, C
1
-C
4
-halogenoalkyl-, C
1
-C
4
-alkoxy-, C
1
-C
4
-halogenoalkoxy-, C
1
-C
4
-alkylthio-, C
1
-C
4
-halogenoalkylthio-, C
1
-C
4
-alkylsulphinyl-, C
1
-C
4
-halogenoalkylsulphinyl-, C
1
-C
4
-alkylsulphonyl-, C
1
-C
4
-halogenoalkylsulphonyl-, C
1
-C
4
-alkoxy-carbonyl- or di-(C
1
-C
4
-alkyl)-amino-substituted aryl having 6 or 10 carbon atoms.
In the formula (III)
A in particular represents SO
2
or CO and
R in particular represents in each case optionally cyano-, fluorine-, chlorine-, methoxy- or ethoxy-substituted methyl, ethyl, n- or i-propyl, n-, i-, s- or t-butyl, or in particular represents optionally cyano-, nitro-, fluorine-, chlorine-, bromine-, methyl-, ethyl-, n- or i-propyl-, n-, i-, s- or t-butyl-, trifluoromethyl-, methoxy-, ethoxy-, n- or i-propoxy-, difluoromethoxy-, trifluoromethoxy-, methylthio-, ethylthio-, n- or i-propylthio-, trifluoromethylthio-, methylsulphinyl-, ethylsulphinyl-, n- or i-propylsulphinyl-, trifluoromethylsulphinyl-, methylsulphonyl-, ethylsulphonyl-, n- or i-propylsulphonyl-, trifluoromethylsulphonyl-, methoxycarbonyl-, ethoxycarbonyl-, n- or i-propoxy-carbonyl-, dimethylamino- or diethylamino-substituted phenyl.
The starting materials of the general formula (III) are known organic chemicals for synthesis.
The process according to the invention is carried out using an acid acceptor. Suitable acid acceptors are, in general, the customary inorganic or organic bases or acid acceptors. These preferably include alkali metal or alkaline earth metal acetates, amides, carbonates, bicarbonates, hydrides, hydroxides or alkoxides, such as, for example, sodium acetate, potassium acetate or calcium acetate, lithium amide, sodium amide, potassium amide or calcium amide, sodium carbonate, potassium carbonate or calcium carbonate, sodium bicarbonate, potassium bicarbonate or calcium bicarbonate, lithium hydride, sodium hydride, potassium hydride or calcium hydride, lithium hydroxide, sodium hydroxide, potassium hydroxide or calcium hydroxide, sodium methoxide, ethoxide, n- or i-propoxide, n-, i-, s- or t-butoxide or potassium methoxide, ethoxide, n- or i-propoxide, n-, i-, s- or t-butoxide; furthermore also basic organic nitrogen compounds, such as, for example, trimethylamine,
Hupperts Achim
Lantzsch Reinhard
Bayer Aktiengesellschaft
Gil Joseph C.
O'Sullivan Peter
LandOfFree
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