Ferrocenyl diphosphines and their use

Details Ferrocenyl diphosphines and their use Ferrocenyl diphosphines and their use

2002-12-31

2004-08-17

Nazario-Gonzalez, Porfirio (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heavy metal containing

C556S014000, C556S021000, C502S154000, C502S155000, C585S274000, C585S276000, C585S277000

Reexamination Certificate

active

06777567

ABSTRACT:

The present invention relates to 1-(&agr;-secondary-phosphinoalkyl)-2-(secondary-phosphinoaryl) ferrocenyls; a process for preparing these ferrocenyl diphosphines and intermediates; metal complexes comprising metals selected from transition groups I and VIIl of the Periodic Table of the Elements (d-10 and d-8 metals, hereinafter referred to as TM8 metals) and these ferrocenyl disphosphines; a process for asymmetric synthesis by addition of hydrogen, borohydrides or silanes onto a carbon-carbon or carbon-heteroatom multiple bond in prochiral organic compounds or addition of carbon nucleophiles, alcohols or amines onto allylic compounds, and particularly for the asymmetric hydrogenation of carbon-carbon or carbon-heteroatom multiple bonds by means of hydrogen, in the presence of catalytic amounts of the metal complexes; and the use of the metal complexes as catalysts for asymmetric synthesis by addition of hydrogen, borohydrides or silanes onto carbon-carbon or carbon-heteroatom multiple bonds in prochiral organic compounds or of carbon nucleophiles, alcohols or amines onto allylic compounds, and particularly for the asymmetric hydrogenation of carbon-carbon or carbon-heteroatom multiple bonds by means of hydrogen.
U.S. Pat. Nos. 5,371,256, 5,446,844 and 5,583,241 describes C
2
-symmetric 1-(&agr;-secondary-phosphinoalkyl)-2-secondary-phosphinoferrocenyls as ligands for metal complexes which are, inter alia, excellent homogeneous catalysts for the asymmetric hydrogenation of organic compounds having multiple bonds.
In Angew. Chem. 1999, 111, No. 21, pages 3397 to 3400, T. Ireland et al. disclose C
2
-symmetric 1-[&agr;-(2′-secondary-phosphinophen-1′-yl-alkyl)]-2-secondary-phosphinoferrocenyls as ligands for metal complexes; the ruthenium and rhodium complexes of these ligands are effective catalysts in the enantioselective hydrogenation of &bgr;-keto esters or &bgr;-ketones or of methyl &agr;-acetamidocinnamate or dimethyl itaconate.
It has now surprisingly been found that C
1
-symmetric secondary diphosphines having a ferrocenyl-aryl skeleton are valuable ligands for TM8 metal complexes which are excellent homogeneous catalysts for asymmetric syntheses, particularly for the asymmetric hydrogenation of carbon-carbon and carbon-heteroatom multiple bonds. A particular advantage of the ligands is that excellent enantioselectivities are retrieved when using prochiral carboxylic acids.
The invention firstly provides compounds of the formulae I and Ia in the form of racemates, mixtures of diastereomers or in essentially enantiomerically pure form,
where
R is hydrogen, C
1
-C
8
alkyl, C
5
-C
12
cycloalkyl, phenyl or phenyl substituted by from 1 to 3 C
1
-C
4
alkyl or C
1
-C
4
alkoxy groups;
n is 0 or an integer from 1 to 4 and R′ are identical or different substituents selected from the group consisting of C
1
-C
4
alkyl, C
1
-C
4
fluoroalkyl and C
1
-C
4
alkoxy;
X
1
and X
2
are each, independently of one another, secondary phosphino;
T is C
6
-C
20
arylene or C
3
-C
16
heteroarylene;
and X
2
is bound in the ortho position relative to the T-cyclopentadienyl bond.
Preference is given to compounds of the formulae Ib and Ic in the form of racemates, mixtures of diastereomers or in essentially enantiomerically pure form,
where
R is hydrogen, C
1
-C
8
alkyl, C
5
-C
12
cycloalkyl, phenyl or phenyl substituted by from 1 to 3 C
1
-C
4
alkyl or C
1
-C
4
alkoxy groups;
n is 0 or an integer from 1 to 4 and R′ are identical or different substituents selected from the group consisting of C
1
-C
4
alkyl, C
1
-C
4
fluoroalkyl and C
1
-C
4
-alkoxy, or two substituents R′ form the group —CH═CH—CH═CH— which may be unsubstituted or substituted by C
1
-C
4
alkyl or C
1
-C
4
alkoxy; and
X
1
and X
2
are each, independently of one another secondary phosphino.
An alkyl group R is preferably a linear C
1
-C
4
alkyl, for example methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl or octyl. Preferred alkyls are ethyl and, in particular, methyl.
A cycloalkyl group R is preferably C
5
-C
6
cycloalkyl, for example cyclopentyl or cyclohexyl.
An arylene group T preferably contains from 6 to 14 carbon atoms. Examples of arylene are phenylene, naphthylene, anthracylene and phenanthrylene. Preference is given to phenylene and naphthylene.
A heteroarylene group T preferably contains from 5 to 14 carbon atoms. The heteroatoms are preferably selected from the group consisting of O, S and N. The heteroarylene can contain from 1 to 4, preferably 1 or 2, identical or different heteroatoms. A few examples are pyridinylene, pyrimidinylene, pyrazinylene, pyrrolylene, furanylene, oxazolylene, imidazolylene, benzofuranylene, indolylene, benzimidazolylene, quinolylene, isoquinolylene, quinazolinylene and quinoxalinylene.
Examples of phenyl substituted by from 1 to 3 C
1
-C
4
alkyl or C
1
-C
4
alkoxy groups as R are tolyl, xylyl, trimethylphenyl, methoxyphenyl, ethoxyphenyl and dimethoxyphenyl.
R is preferably hydrogen, C
1
-C
4
alkyl, cyclopentyl, cyclohexyl or phenyl. R is very particularly preferably hydrogen, methyl, ethyl, n-propyl or n-butyl.
When R is a substituent, the compounds preferably correspond to the formula Id or Ie,
where T, R, R′, n, X
1
and X
2
are as defined above.
When R is a substituent, the compounds particularly preferably correspond to the formula If or Ig,
where R, R′, n, X
1
and X
2
are as defined above.
An alkyl group R′ preferably contains 1 or 2 carbon atoms. Preference is given to linear alkyl. Examples of alkyl groups R′ are methyl, ethyl, n- and i-propyl, n-, i- and t-butyl. Preference is given to methyl and ethyl and particular preference is given to methyl.
Alkoxy groups R′ preferably contain 1 or 2 carbon atoms. Preference is given to linear alkoxy. Examples of alkoxy groups R′ are methoxy, ethoxy, n- and i-propoxy, n-, i- and t-butoxy. Preference is given to methoxy and ethoxy and particular preference is given to methoxy.
A fluoroalkyl group R′ is preferably trifluoromethyl.
In the formulae I to Ie, n is preferably 0, 1 or 2, particularly preferably 0 or 1.
The individual phosphine groups X
1
and X
2
may contain two identical or two different hydrocarbon radicals, or the two hydrocarbon radicals together with the P atom can form a three- to eight-membered ring. The individual phosphine groups preferably contain two identical hydrocarbon radicals, and different phosphine groups of this type may be bound to the ferrocenyl skeleton. The hydrocarbon radicals may be unsubstituted or substituted and may contain from 1 to 22, preferably from 1 to 12, carbon atoms. Among the compounds of the formula I, particular preference is given to ones in which the individual phosphine groups contain two identical or different radicals selected from the group consisting of linear or branched C
1
-C
12
alkyl; unsubstituted or C
1
-C
6
alkyl- or C
1
-C
6
alkoxy-substituted C
5
-C
12
cycloalkyl or C
5
-C
12
cycloalkyl-C
2
—; phenyl or benzyl; or phenyl or benzyl substituted by halogen (for example F, Cl and Br), C
1
-C
6
alkyl, C
1
-C
6
haloalkyl (for example trifluoromethyl), C
1
-C
6
alkoxy, C
1
-C
6
haloalkoxy (for example trifluoromethoxy), (C
6
H
5
)
3
Si, (C
1
-C
12
alkyl)
3
Si, secondary amino or —CO
2
—C
1
-C
6
alkyl (for example —CO
2
CH
3
).
The two radicals in the phosphine groups can together also be unsubstituted or halogen-, C
1
-C
6
-alkyl- or C
1
-C
6
-alkoxy-substituted dimethylene, trimethylene, tetramethylene or pentamethylene. The substituents are preferably bound in the two ortho positions relative to the P atoms.
The phosphine groups can also be groups of the formulae
where o and p are each, independently of one another, an integer from 2 to 10, and the sum o+p is from 4 to 12, preferably from 5 to 8, and the phenyl rings are unsubstituted or substituted by C
1
-C
4
-alkyl and C
1
-C
4
-alkoxy. Examples are [3.3.1]phobyl and [4.2.1]phobyl of the formulae
Examples of secondary phosphine groups in which the two hydrocarbon radicals together with the P atom form a 3-

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