6′,6-bis-(1-phosphanorbornadiene) diphosphines

Details 6′,6-bis-(1-phosphanorbornadiene) diphosphines 6′,6-bis-(1-phosphanorbornadiene) diphosphines

2000-01-13

2001-09-11

Vollano, Jean F. (Department: 1621)

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

Organic compounds

Phosphorus containing

Reexamination Certificate

active

06288279

ABSTRACT:

A subject of the present invention is new 6,6′-bis-(1-phosphanorbornadiene) diphosphines and their preparation process.
Another subject of the invention is said optically active disphosphines.
Finally, other subjects are the uses of these diphosphines, in particular in asymmetrical synthesis in organic chemistry.
In numerous fields, in particular pharmaceutical, agro-chemical or perfumery fields, a growing demand has been noted for optically active products which must have a useful property.
During synthesis of such products, the simultaneous production of an inactive enantiomer is generally observed which, by its presence, risks rendering a process uncompetitive from an industrial point of view.
Moreover, in certain fields (for example, pharmacology and agrochemistry), optically pure products are increasingly sought after, in order to avoid toxicity problems linked to the presence of the inactive enantiomer.
It is therefore important to minimize the formation of the enantiomer, which is not useful.
One of the means of achieving this is to conduct the reaction in the presence of asymmetrical synthesis catalysts, which can be complexes of transition metals with chiral ligands.
The problem which arises is that there are no universal chiral ligands which are suitable for conducting all chemical reactions and, given the difficulty of obtaining the correct enantiomer with a high enantiomeric excess, it is important to have all sorts of chiral ligands available in order to assess their performances.
Thus, in the Application PCT/FR95/01716, new optically active 6,6′-bis-(1-phospha-2,3-diphenyl-4,5-dimethylnorbornadiene) diphosphines were described, corresponding to the following formulae:
While this ligand allows useful hydrogenation catalysts to be obtained for hydrogenating certain a,b-unsaturated acids such as a-acetamidocinnamic acid, the enantiomeric excess obtained is not satisfactory in all asymmetrical catalysis reactions.
It is therefore desirable to have other chiral ligands available which can be suitable if known ligands are insufficiently enantioselective.
The difficulty is that chiral ligands of diphosphine type are not easily accessible owing to their complex synthesis and also to the difficulty in separating diastereoisomers and/or enantiomers.
A first objective of the invention is to provide new diphosphines and a process for their preparation.
Another objective is to provide optically active diphosphines, chiral as regards phosphorus and non-racemizable.
Another objective is to provide modified diphosphines allowing better results to be obtained in asymmetrical catalysis reactions.
New products have now been found constituting the first subject of the invention, namely 6,6′-bis-(1-phosphanorbornadiene) diphosphines corresponding to the following formula:
in said formula (I):
R
1
, R
2
, R
3
, R
4
, R
5
, identical or different, represent a hydrogen atom or hydrocarbon radical, optionally substituted, having from 1 to 40 carbon atoms, which can be a linear or branched, saturated or unsaturated acyclic aliphatic radical; a monocyclic or polycyclic, saturated, unsaturated or aromatic, carbocyclic or heterocyclic radical; a linear or branched, saturated or unsaturated aliphatic radical, carrying a cyclic substituent,
R
2
and R
3
together with the carbon atoms which carry them can form a saturated or unsaturated ring,
R
5
can represent a radical of
 type, in which R
1
′, R
2
′ and R
3
′ have the same meaning as that given for R
1
, R
2
and R
3
,
R
4
, and R
5
cannot simultaneously represent a phenyl group.
In general formula (I), R
1
, R
2
, R
3
, R
4
, R
5
, identical or different, can assume various meanings. Different examples are given hereafter but are in no way limitative.
Thus R
1
to R
5
can represent a linear or branched, saturated or unsaturated, acyclic aliphatic radical.
More precisely, R
1
to R
5
represent a linear or branched acyclic aliphatic radical preferably having 1 to 12 carbon atoms, saturated or comprising one to several, generally 1 to 3, double bonds.
The hydrocarbon chain can optionally be interrupted by a group, preferably a heteroatom, and more particularly an oxygen or nitrogen atom or can carry substituents, for example a halogen atom, in particular chlorine or a —CF
3
group.
It is also possible that in the diphosphine of formula (I), R
1
to R
5
represent a linear or branched, saturated or unsaturated acyclic aliphatic radical which can optionally carry a cyclic substituent. By ring is understood a saturated, unsaturated or aromatic, carbocyclic or heterocyclic ring.
As examples of cyclic substituents, aromatic or heterocyclic cycloaliphatic substituents can be envisaged, in particular cycloaliphatic substituents comprising 6 carbon atoms in the ring or benzene substituents, these cyclic substituents themselves optionally carrying one or more substituents.
As examples of such radicals there can be mentioned amongst others the benzyl radical.
In general formula (I) for diphosphines, the R
1
to R
5
radicals can also represent a carbocyclic radical, saturated or comprising 1 or 2 unsaturations in the ring, generally having 3 to 8 carbon atoms, preferably 6 carbon atoms in the ring; said ring being able to be substituted.
As preferred examples of R
1
to R
5
radicals, there can be mentioned the cyclohexyl radicals optionally substituted by linear or branched alkyl radicals having 1 to 4 carbon atoms.
R
1
to R
5
can be saturated or unsaturated polycyclic carbocyclic radicals, preferably bicyclic, which means that at least two rings have two carbon atoms in common. In the case of the polycyclic compounds, the number of carbon atoms in each ring preferably varies from 3 to 6: the total number of carbon atoms preferably being equal to 7.
Thus, the R
1
to R
5
radicals preferentially represent an aromatic hydrocarbon radical, and in particular a benzene radical corresponding to general formula (II):
in said formula (II):
n is an integer from 0 to 5, preferably from 0 to 3,
Q represents R
0
, one of the following groups or functions:
a linear or branched alkyl radical having from 1 to 6 carbon atoms, preferably from 1 to 4 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl,
a linear or branched alkenyl radical having from 2 to 6 carbon atoms, preferably from 2 to 4 carbon atoms, such as vinyl, allyl,
a linear or branched alkoxy radical having from 1 to 6 carbon atoms, preferably from 1 to 4 carbon atoms such as the methoxy, ethoxy, propoxy, isopropoxy, butoxy radicals,
an acyl group having from 2 to 6 carbon atoms,
a radical of formula:
—R
6
—OH
—R
6
—COOR
7
—R
6
—CHO
—R
6
—NO
2
—R
6
—CN
—R
6
—N(R
7
)
2
—R
6
—CO—N(R
7
)
2
—R
6
—SH
—R
6
—X
—R
6
—CF
3
—O—CF
3
in said formulae, R
6
represents a valency bond or a saturated or unsaturated, linear or branched, divalent hydrocarbon radical having from 1 to 6 carbon atoms such as, for example, methylene, ethylene, propylene, isopropylene, isopropylidene; the R
7
radicals, identical or different, represent a hydrogen atom or a linear or branched alkyl radical having from 1 to 6 carbon atoms; X symbolizes a halogen atom, preferably a chlorine, bromine or fluorine atom.
Q represents R
0
′, one of the following more complex radicals:
 in which:
m is an integer from 0 to 5, preferably from 0 to 3,
R
0
has the meaning indicated previously,
R
8
represents a valency bond; a saturated or unsaturated, linear or branched divalent hydrocarbon group having from 1 to 6 carbon atoms such as for example methylene, ethylene, propylene, isopropylene, isopropylidene or one of the following groups called Z:
—O—; —CO—; COO—; —NR
7
—; —CO—NR
7
—; —S—; —SO
2
—; —NR
7
—CO—;
in said formulae, R
7
represents a hydrogen atom, a linear or branched alkyl group having from 1 to 6 carbon atoms, preferably a methyl or ethyl radical.
When n is greater than 1, the Q radicals can be identical or different and 2 successive carbon atoms of the benzene ring can be joined together by a ketal bridge such as the extranucl

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