Organic compounds -- part of the class 532-570 series – Organic compounds – Nitriles
Reexamination Certificate
2001-07-18
2002-11-26
Solola, T. A. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Nitriles
Reexamination Certificate
active
06486340
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for producing an &agr;-aminonitrile by aerobic oxidation of a tertiary amine with a cyanide by using a transition metal catalyst.
2. Related Art Statement
In the fields of medicinal and material sciences, the necessity for the nitrogen-containing organic compounds has been increasing in recent years, and development of efficient and selective methods for constructing carbon skeletons of nitrogen-containing organic compounds has been urgently required. An &agr;-aminonitrile is obtained by cyanating carbon at a position adjacent to a nitrogen atom of a tertiary amine through catalytic oxidation with oxygen. Since this &agr;-aminonitrile is easily converted to an amino acid as well as various nitrogen-containing biologically active materials, the utility of the reaction is high.
It is known that such &agr;-aminonitriles are obtained by employing anode oxidation (J. Am. Chem. Soc. 91, 4181 (1969), a photo reaction (Tetrahedron Lett. 31, 4735 (1990), chlorine dioxide (J. Am. Chem. Soc. 110, 4829 (1988), a benzoiodine xole (Tetrahedron Lett. 36, 7975 (1995)), or cyano iodine or the like. However, the above reactions are not industrially proper methods, since these should employ special reaction apparatuses, special reaction reagents that are difficult to obtain a large amount.
The present inventors discovered a method for producing &agr;-aminonitriles by the reaction of tertiary amines with trimethylsilyl cyanide in the presence of ruthenium chloride and peracetic acid (Japanese Chemical Society No. 70 Spring Season Annual Report 3J247). However, this method since it uses relatively expensive trimethylsilyl and peracetic acid and gives many byproducts needed further improvement for an industrial process. After further investigation in view of this, the present inventors discovered a method for producing &agr;-aminonitriles from tertiary amines by using metal cyanides and hydrogen peroxide both of which are inexpensive and easily available (JP-A 11-255,729). Although this method can produce the &agr;-aminonitriles relatively inexpensively, the efficient method using molecular oxygen, a method using a safer and cheaper oxidant, has been demanded to be developed.
SUMMARY OF THE INVENTION
Having examined oxidizing agents that satisfies sufficient safety and economy for industry process, the present inventors discovered that &agr;-aminonitriles are obtained by oxidizing tertiary amines with molecular oxygen, and reached the invention based on this discovery. That is, the present invention is to provide a method for producing an &agr;-aminonitrile, comprising the step of oxidizing a tertiary amine with oxygen by using a transition metal catalyst in the presence of a cyanide.
DETAILED DESCRIPTION OF THE INVENTION
(1) Tertiary Amines
As the tertiary amine for a starting material is preferable a tertiary amine that is represented by a general formula R
1
R
2
NCH
2
R
3
in which R
1
is a phenyl group which may be substituted, R
2
is an alkyl group or a phenyl group which may be substituted, R
3
is a hydrogen atom, an alkyl group or a phenyl group which may be substituted, provided that R
1
and R
3
or R
2
and R
3
may be bonded to form a nitrogen-containing ring.
(1-1) Substituting Group R
1
As the phenyl group, which may be substituted, in the substituting group R
1
of the compound represented by the general formula R
1
R
2
NCH
2
R
3
, mention may be made of, for example, phenyl group, lower alkyl-substituted phenyl groups such as 2-methylphenyl group, 3-methylphenyl group and 4-methylphenyl group, halogen-substituted phenyl groups such as 2-chlorophenyl group, 3-chlorophenyl group, 4-chlorophenyl group, 2-bromophenyl group, 3-bromophenyl group and 4-bromophenyl group, lower alkoxyphenyl groups such as 2-methoxyphenyl group, 3-methoxyphenyl group and 4-methoxyphenyl group, etc.
(1-2) R
2
, R
3
, etc.
As the alkyl groups for R
2
and R
3
, mention may be made of, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, s-butyl group, t-butyl group, pentyl group, hexyl group and cyclohexyl group. As the phenyl group which may be substituted, mention may be made of, for example, phenyl group, lower alkyl-substituted phenyl groups such as 2-methylphenyl group, 3-methylphenyl group and 4-methylphenyl group, halogen-substituted phenyl groups such as 2-chlorophenyl group, 3-chlorophenyl group, 4-chlorophenyl group, 2-bromophenyl group, 3-bromophenyl group and 4-bromophenyl group, lower alkoxyphenyl groups such as 2-methoxyphenyl group, 3-methoxyphenyl group and 4-methoxyphenyl group, etc.
As the nitrogen-containing ring which is formed when R
2
and R
3
are bonded to each other, mention may be made of piperidine, pyrrolidine, N-phenyl-1,2,3,4-tetrahydroisoquinoline, etc. As the nitrogen-containing ring which is formed when R
1
and R
3
are bonded to each other, mention may be made of 1, 2, 3, 4-tetrahydroisoquinoline, etc.
As specific examples for the tertiary amines, mention may be made of N,N-dimethylaniline, N-ethyl-N-methylaniline, N,N-diethylaniline, N-phenyl-N-methylaniline, N,N,4-trimethylaniline, N,N-dimethyl-4-bromoaniline, N,N-dimethyl-4-methoxyaniline, N-phenylpiperidine, N-(4-methoxyphenyl)piperidine, N-phenyl-1,2,3,4-tetrahydroisoquinoline, 6-benzyloxy-N-phenyl-7-methoxy-1, 2,3,4-tetrahydroxyisoquinoline, etc.
(2) Cyanide
As the cyanide for a starting material, alkali metal cyanides such as sodium cyanide and potassium cyanide, hydrogen cyanide or trimethylsilyl cyanide is preferred. From the reactivity and economical points of view, sodium cyanide and potassium cyanide are preferably used.
Although the use amount of the cyanide is not particularly limited, it is ordinarily 1 to 10 times in mole, preferably 1 to 3 times in mole as much as that of a substrate (tertiary amine). The cyanide may be used as it is, or in the form of a solution in which the cyanide is dissolved in a solvent mentioned later.
(3) &agr;-Aminonitrile
The &agr;-aminonitrile obtained in the present invention is preferably represented by a general formula R
1
R
2
NCH(CN)R
3
in which R
1
is a phenyl group which may be substituted, R
2
is an alkyl group or a phenyl group which may be substituted, R
3
is a hydrogen atom, an alkyl group or a phenyl group which may be substituted, provided that R
1
and R
3
or R
2
and R
3
may be bonded to form a nitrogen-containing ring. Those recited in the above (1-1) and (1-2) are employed as specific examples for the R
1
, R
2
and R
3
.
As specific examples for the &agr;-aminonitrile of the general formula R
1
R
2
NCH(CN)R
3
produced by the present invention, mention may be made of, for example, N-phenyl-N-methylaminoacetonitrile, N-phenyl-N-ethylamino-acetonitrile, 2-(N-ethyl-N-phenylamino)propionitrile, N,N-diphenylamino-acetonitrile, N-(4-methylphenyl)-N-methylaminoacetonitrile, N-(4-bromophenyl)-N-methylaminoacetonitrile, N-(4-methoxyphenyl)-N-methylaminoacetonitrile, 2-cyano-N-phenylpiperidine, 2-cyano-N-(4-methoxyphenyl)piperidine, 1-cyano-N-phenyl-1, 2,3,4-tetrahydroxyisoquinoline, 1-cyano-6-benzyloxy-N-phenyl-7-methoxy-1, 2,3,4-tetrahydroisoquinoline, etc.
(4) Transition Metal Catalysts
As the transition metal catalyst used in the present invention, one or more transition metal catalysts selected from the group consisting of a ruthenium-based catalyst, a chromium-based catalyst, a manganese-based catalyst, an iron-based catalyst, a cobalt-based catalyst, a nickel-based catalyst and a palladium-based catalyst are preferred. For example, use may be made of ruthenium catalysts such as RuCl
3
-nH
2
O, n-Pr
4
NRuO
4
, Ru
2
(&mgr;-OAc)
4
Cl, Ru
3
(&mgr;-O) (&mgr;-OAc)
6
(H
2
O)
3
, RuO
2
, KRuO
4
, RuCl
2
(PPh
3
)
3
, RuCl
2
(bpy)
2
, Ru(acac)
3
and K
4
Ru(CN)
6
, chromium-based catalyst such as CrCl
2
, manganese-based catalysts such as MnCl
2
, iron-based catalysts such as FeCl
3
, cobalt-based catalysts such as CoCl
2
, nickel-based catalysts such as NiCl
2
and palladium-based catalysts such as PdCl
2
. Among them, RuCl
3
-nH
2
O is p
Komiya Naruyoshi
Murahashi Shun-ichi
Burns Doane , Swecker, Mathis LLP
Murray Joseph
Osaka University
Solola T. A.
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