Patent EA-003733-B1 (EA)
Title: Method for producing (hetero)aromatic hydroxylamines
Inventor: KLINTZ RALF
IPC: C07C251/58
Filed: 1998-08-21
Abstract: 1. A process for the preparation of N-acylated (hetero)aromatic hydroxylamine derivatives of the formula I wherein the substituents, the ring atom and the index have the following meanings: R<1> is hydrogen, halogen, cyano, C1-C4alkyl, C1-C4haloalkyl, C1-C4alkoxy, C1-C4haloalkoxy, C1-C4alkylthio, C1-C4alkylcarbonyl, C1-C4dialkylaminocarbonyl, C1-C4alkylcarbonylamino, C1-C4alkylcarbonyl-C1-C6alkylamino, C1-C4alkoxycarbonyl, -CH2O-N=C(R<A>)-C(R<B>)=N-O-R<C>, -CH2-O-N=C(R<D>)- C1-C4alkyl, or a group A-B, where A is -O-, -CH2-, -O-CH2-, -CH2-O-, -CH2-O-CO-, -CH=CH-, -CH=N-O-, -CH2-O-N=C(R<A>)- or a single bond, B is phenyl, naphthyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, pyrazolyl, imidazolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, 1,2,4-triazolyl, 1,2,3-triazolyl, furanyl, thienyl, pyrrolyl or C3-C7-cycloalkyl, where B may be substituted by 1-3 substituents R, R is hydrogen, halogen, cyano, C1-C4alkyl, C1-C4haloalkyl, C1-C4alkoxy, C1-C4haloalkoxy, C1-C4alkylthio, C1-C4alkylcarbonyl, C1-C4alkyl-C(R<D>)=N-O-C1-C4alkylene, C1-C4alkoxycarbonyl, C1-C4alkylaminocarbonyl, C1-C4C1-C4-dialkylaminocarbonyl, C1-C4C1-C4-alkylcarbonylamino, C1-C4alkylcarbonyl- C1-C4alkylamino or phenyl which itself may be substituted by halogen or C1-C4alkyl, R<A> and R<C> are each hydrogen, halogen, cyano, C1-C4alkyl, C1-C4alkoxy, C1-C4alkylthio, cyclopropyl or trifluoromethyl, R<B> is C1-C4alkyl, C2-C4alkenyl, C3-C6-cycloalkyl, phenyl, hetaryl or heterocyclyl, R<D> independently of one another, are hydrogen, C1-C4alkyl, C2-C4-alkenyl, or C2-C4-alkynyl, R<2> is halogen, C1-C4alkyl, C1-C4haloalkyl or C1-C4alkoxycarbonyl, X is N or CH and n is 0, 1, 2 or 3, it being possible for the radicals, R<2> to be different when n is greater than 1, by hydrogenating a (hetero)aromatic nitro compound of the formula II where R, X and R<2> have the above mentioned meanings, in the presence of a hydrogenation catalyst, wherein the hydrogenation is carried out in a mixture comprising a solvent selected from the group including an aliphatic and aromatic ether (e.g. tetrahydrofuran), an aliphatic and aromatic hydrocarbon (e.g. benzene, toluene, and chlorobenzene) and primary C1-C4alkylamine, wherein a complex compound Pt-(phenylazo)2 based on alumina can not be a catalyst. 2. A process as claimed in claim 1 for the preparation of (hetero)aromatic compounds of the formula I, where R<1> is -CH2-O-N=C(R<A>)-C(R<B>)=N-O-R<C>, C1-C4alkyl-CR<D>=N-O-CH2 or the group A-B where A, B, R<A>, R<B>, R<C> and R<D> and R<2>, X and n have the meanings stated in claim 1. 3. A process as claimed in either of claims 1 and 2, wherein the C1-C4alkylamine has a boiling point below that of the solvent. 4. A process as claimed in any of claims 1, 2 and 3, wherein the hydrogenation is carried out in a mixture of an aromatic or aliphatic hydrocarbon and a primary C1-C4alkylamine. 5. A process as claimed in any of claims 1, 2 and 3, wherein palladium or platinum, in the presence or absence of an active carbon carrier, is used as the hydrogenation catalyst. 6. A process as claimed in any of claims 1, 2 and 3, wherein Raney nickel or Raney cobalt is used as the hydrogenation catalyst. 7. A process as claimed in any of claims 1, 2 and 3, wherein the primary C1-C4alkylamine is used in a molar ratio of from 1 to 15, based on the nitro compound II. 8. A process as claimed in any of claims 1, 2 and 3, wherein the concentration of the primary C1-C4alkylamine in the solvent is from 0.1 to 20% by weight. 9. A process for the preparation of N-acylated (hetero)aromatic hydroxylamine derivatives of the formulae III and IV, wherein after hydrogenation is complete, the amine is removed by distillation or extraction and the hydroxylamine I thus obtained, without further purification, is N-acylated to give the compounds of the formula III where R<1> and R<2>, the ring atom X and n have the meanings stated in claim 2 and R<3> is C1-C4alkoxycarbonyl, C1-C4alkylcarbonyl, C1-C4alkylaminocarbonyl or di(C1-C4alkyl)aminocarbonyl, with the aid of an acylating agent R<3>-L<1>, where L<1> is a nucleophilic leaving group, such as halide, hydroxide, anhydride or isocyanate, and then, if required, O-alkylated to give the compounds of the formula IV where R<1>, R<2> and R<3>, the ring atom X and n have the above mentioned meanings and R<4> is C1-C6alkyl, with the aid of an alkylating agent R<4>-L<2>, where L<2> is a nucleophilic leaving group, such as halide, sulfate or sulfonate.