Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing
Reexamination Certificate
2001-09-06
2002-04-02
Barts, Samuel (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Amino nitrogen containing
C564S432000, C564S435000, C564S407000, C564S405000, C564S307000
Reexamination Certificate
active
06365776
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a process for producing aromatic amines by the reaction between aromatic compounds having a releasable group and amines. More particularly, it relates to a process for producing an aromatic amine by the reaction between an aromatic compound having a releasable group and an amine in the presence of a palladium catalyst having a phosphine sulfide as a ligand. The aromatic amines obtained by the process are useful as a material of organic electronic materials and pharmaceuticals.
BACKGROUND ART
A number of proposals have been reported on production of aromatic amines by condensation of an aryl halide and an amine. For example, the latest development of an Ullmann reaction in the presence of a copper catalyst is reported in
JOC,
p. 670 (1999). The feature of this reaction, which is also a demerit, lies in that only an iodide, which is highly reactive, is usable as an aryl halide so that a less expensive bromide cannot be used.
On the other hand, it is known that use of a palladium compound as a catalyst enables use of either a bromide or a chloride as an aryl halide substrate. For example, Buchwald et al. and Hartwig et al. show methods in which a phosphine is used as an activator (see
Acc. Chem. Res.,
vol. 31, pp 805 and 852 (1998)). However, phosphines as an activator are generally susceptible to oxidation and need care in handling.
The phosphine's susceptibility to oxidation makes the arylamination reaction using a phosphine as an activator very sensitive to the type or quality of the phosphine, and a more stable activator that can take the place of a phosphine has been sought. Accordingly, an object of the present invention is to provide a more stable activator in arylamination using a palladium compound as a catalyst.
SUMMARY OF THE INVENTION
As a result of extensive investigation, the inventors of the present invention have found that a phosphine sulfide which is impervious to oxidation acts as an effective ligand activating a palladium catalyst thereby to activate the arylamination reaction significantly. The present invention has been completed based on this finding.
The present invention provides a process of producing an aromatic amine comprising allowing an aromatic compound having a releasable group to react with an amine in the presence of a phosphine sulfide and a palladium compound, for example, as described below.
(1) A process for producing an aromatic amine comprising allowing an aromatic compound having a releasable group to react with an amine in the presence of a phosphine sulfide and a palladium compound.
(2) A process according to (1) above, wherein the reaction is carried out in the presence of a base.
(3) A process according to (1) or (2) above, wherein said releasable group is a halogen atom, a trifluoromethanesulfonyloxy group, a methanesulfonyloxy group or a p-toluenesulfonyloxy group.
(4) A process according to (1) or (2) above, wherein said releasable group is a halogen atom.
(5) A process according to any one of (1) to (4) above, wherein said phosphine sulfide is a compound represented by formula (I):
wherein R
1
, R
2
, R
3
each represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted alkenyl group or a substituted or unsubstituted aryl group; and any two of R
1
, R
2
and R
3
may be connected to each other to form an alkylene chain; provided that at least one of R
1
, R
2
and R
3
is an alkenyl group or an aryl group.
(6) A process according to any one of (1) to (5) above, wherein said amine is a primary amine, a secondary amine, an imine or an amide.
Compared with the reaction using a phosphine as an activator, the reaction using a phosphine sulfide as an activator shows an apparently improved selectivity to provide a desired aromatic amine in a noticeably increased yield. This fact obviously denies the assumption that a phosphine sulfide may be reduced to phosphine in the reaction system to participate in the reaction.
The phosphine sulfide which can be used in the present invention includes compounds represented by formula (I):
wherein R
1
, R
2
, R
3
each represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted alkenyl group or a substituted or unsubstituted aryl group; and any two of R
1
, R
2
and R
3
may be connected to each other to form an alkylene chain; provided that at least one of R
1
, R
2
and R
3
is an alkenyl group or an aryl group.
In formula (I), the alkyl group, which may be substituted or unsubstituted, represented by R
1
, R
2
and R
3
includes a straight-chain or branched alkyl group having 1 to 20, preferably 1 to 10, still preferably 1 to 6, carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, t-butyl, pentyl and hexyl. The alkyl group may have any substituent(s) that would not adversely affect the arylamination reaction.
The cycloalkyl group, which may be substituted or unsubstituted, includes a monocyclic, polycyclic or condensed cycloalkyl group having 3 to 30, preferably 3 to 20, still preferably 3 to 10, carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl and cyclooctyl. The cycloalkyl group may have any substituent(s) that would not adversely affect the arylamination reaction.
The alkenyl group includes a vinyl group, an allyl group, etc., each of which may be substituted with the above-described alkyl group, a phenyl group, etc. Specific examples of the alkenyl group are vinyl, allyl, 1-methyl-2,2-diphenylvinyl, and 1,2,2-triphenylvinyl.
The aryl group, which may be substituted or unsubstituted, includes a monocyclic, polycyclic or condensed aromatic hydrocarbon group having 6 to 30, preferably 6 to 20, still preferably 6 to 15, carbon atoms, such as phenyl, tolyl, xylyl, naphthyl, methylnaphthyl, and biphenyl. The aryl group can have any substituent(s) that do not cause hindrance to the arylamination reaction.
Examples of the substituent(s) of the substituted alkyl group, substituted cycloalkyl group, substituted alkenyl group, and substituted aryl group include alkyl groups, cycloalkyl groups, alkenyl groups, aryl groups, alkoxy groups, tertiary amino groups, and aryloxy groups, preferably C
1-20
alkyl groups, C
3-30
cycloalkyl groups, C
2-30
alkenyl groups, C
6-20
aryl groups, C
1-20
alkoxy groups, C
2-20
tertiary amino groups, and C
6-20
aryloxy groups. The tertiary amino groups are preferably the groups represented by —N(R
4
)(R
5
) wherein each of R
4
and R
5
independently represents an alkyl group, a cycloalkyl group, an alkenyl group, or an aryl group.
Specific examples of the phosphine sulfides which can be used in the present invention are triphenylphosphine sulfide, P,P-dicyclohexyl-o-biphenylphosphine sulfide, P,P-di-t-butyl-o-biphenylphosphine sulfide, P,P-dicyclohexyl-(1-methyl-2,2-diphenylvinyl)phosphine sulfide, P,P-di-t-butyl-(1-methyl-2,2-diphenylvinyl)phosphine sulfide, P,P-dicyclohexyl-(1,2,2-triphenylvinyl)phosphine sulfide, and P,P-di-t-butyl-(1,2,2-triphenylvinyl)phosphine sulfide.
These compounds are commercially available, which can be used in the invention, or easily obtainable by the reaction between a corresponding phosphine compound and sulfur (see
J. Chem. Soc., Dalton Trans.,
No. 1973, p. 1024).
The aromatic compound having a releasable group which can be used in the invention includes compounds represented by formula (II):
ArX
1
(II)
wherein Ar represents a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaryl group; and X
1
represents a halogen atom, a trifluoromethanesulfonyloxy group, a methanesulfonyloxy group or a p-toluenesulfonyloxy group.
In formula (II), the aryl group Ar, which may be substituted or unsubstituted, includes a monocyclic, polycyclic or condensed aromatic hydrocarbon group having 6 to 30, preferably 6 to 20, still preferably 6 to 15, carbon atoms, such as phenyl, tolyl, xylyl, naphthyl, methylnaphthyl, anthryl, phenathryl and biphenyl. The aryl group ca
Fujiwara Mitsuhiko
Hagiwara Toshimitsu
Hori Yoji
Kobayashi Tohru
Suzuki Ken
Barts Samuel
Sughrue & Mion, PLLC
Takasago International Corporation
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