Chiral diazaphospholidine ligands

Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing

Reexamination Certificate

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C564S012000, C556S013000

Reexamination Certificate

active

06717011

ABSTRACT:

The invention relates to chiral diazaphospholidines, to methods for their preparation, and to their use in catalysts for the asymmetric catalysis of organic reactions.
Catalysts for asymmetric transformations are of great value in organic synthesis. The modification of an organometallic system with a suitable enantiomerically pure ligand is perhaps the most effective and efficient means to achieve this. The most popular of the systems reported to date contain ligands based on phosphorus donors, such as phosphines. The combination of ruthenium with the ligand BINAP was reported by Akutagawa S. (Chirality in Industry, Edt. A. N. Collins el al. (1992), J. Wiley & Sons, Chapter 17, pages 325-329).
DuPHOS, 1,2-(phospholano)benzenes have been demonstrated by Burk el al. (J. Am. Chem. Soc. (1993), vol. 115, pages 10125-10138 and (1998), Vol. 120, pages 657-663) and are the subject of U.S. Pat. No. 5,008,457 and U.S. Pat. No. 5,559,267. Such compounds have been found to be commercially useful, especially as hydrogenation catalysts when used in combination with ruthenium or rhodium.
Brunel J. M. et al (Tet. Lett., (1997), Vol. 38, pages 5971-5974) discloses the use of pyridine-phosphine ligands for enantioselective palladium catalysed substitution allylic substitution. The same group have also disclosed the use of diazaoxaphospholidones, Constantieux T. et al (Synlett, (1998), pages 49-50).
Brunel J. M. et al. (Tet. Lett., (1998), Vol. 39, pages 2961-2964) discloses the use of a pentavalent phosphorus system in the form of o-hydroxyphenyl diazaphospholidine oxide. One of the intermediates used to produce such a compound is a hydroxyphenyl diazaphospholidine. However, this later compound was not tested as a catalyst.
Other diazaphospholidines have been disclosed in the article by Tye et al. (Chem. Commun., (1997) pages 1053-1054).
It is an aim of the current invention to provide novel compounds having improved catalytic properties.
It is also an aim of the current invention to identify compounds which are capable of being produced by industrially applicable processes.
Accordingly, a first aspect of the invention provides a chemical compound represented by Formula 1 or Formula 2.
Where:
A and B are independently selected from C(R
22
R
23
) and C(R
22
R
23
)C(R
24
R
25
) especially CH
2
or (CH
2
)
2
, preferably A and B are the same; R
1
, R
2
, R
3
, R
4
, R
18
, R,
9
, R
20
, R
21
, R
22
, R
23
, R
24
and R
25
each may or may not be present and each may be independently selected from H, halide —OH, —SO
2
R
26
(where R
26
is selected from a group as defined for R
22
, R
23
, R
24
and R
25
), —SH, —NO
2
, —NH
2
, ═O, ═S, straight chain, branched chain, cyclic, saturated, non-saturated, substituted or non-substituted alkyl, hydroalkyl, carboalkyl, alkoxy, amino, alkenyl, aryl and CH
2
Ar (where Ar is aryl or substituted aryl), preferably containing 1 to 6 carbons, more preferably 1 or 2 carbons, or a silane containing 1 to 6 silicon atoms; wherein, where an R
1
, R
2
, R
3
, R
4
, R
18
, R
19
, R
20
, R
21
, R
22
, R
23
, R
24
and/or R
25
group is not present an unsaturated bond is formed; preferably R
1
, R
2
, R
3
and R
4
are identical to R
21
, R
20
, R
19
and R
18
respectively; Preferably R
5
and R
17
are selected from H, —NH
2
, —OH substituted or non-substituted straight or branched chain alkyl or aryl, and halide, preferably the alkyl or aryl is a C
1
, to C
6
alkyl or aryl, more preferably R
5
and R
17
being both the same. R
5
and R
17
may especially be H; R
6
, R
7
, R
15
and R
16
are each independently selected from halide —OH, —SO
2
R
26
, —SH, —NO
2
, —NH
2
, straight chain, branched chain, cyclic, saturated, non-saturated, substituted or non-substituted alkyl, carboalkyl, alkoxy, alkenyl, aryl and CH
2
Ar (where Ar is aryl or substituted aryl), preferably containing 1 to 6 carbons, more preferably 1 or 2 carbons, or a silane containing 1 to 6 silicon atoms, wherein preferably R
6
and R
7
are identical to R
15
and R
16
respectively; R
8
and R
14
are selected from H, straight, branched, cyclic, saturated, non-saturated, substituted or non-substituted alkyl, carboalkyl, alkoxy, alkenyl, aryl and CH
2
Ar (where Ar is aryl or substituted aryl), preferably containing 1 to 6 carbons, phenyl or substituted phenyl being especially preferred, R
8
and R
14
being preferably identical; R
9
, R
10
, R
11
, R
12
, R
13
are independently selected from halide —OH, —SO
2
R
26
, —SH, —NO
2
, —NH
2
, straight chain, branched chain, cyclic, saturated, non-saturated, substituted or non-substituted alkyl, carboalkyl, alkoxy, amino, alkenyl, aryl and CH
2
Ar (where Ar is aryl or substituted aryl), preferably containing 1 to 6 carbons, more preferably 1 or 2 carbons, or a silane, containing 1 to 6 silicon atoms, most preferably R
9
is OMe, R
10
, R
11
, R
12
and R
13
preferably being each H; X is a linking group containing 1 to 12 atoms, preferably the linking group being selected from —S—S—, —O—O—, straight chain, branched chain, cyclic, substituted or non-substituted alkyl, carboalkyl, alkoxy, alkenyl and aryl, preferably X containing 1 to 6 carbon atoms, most preferably X is a disubstituted aromatic moiety.
Preferably the invention provides compounds according to the first aspect of the invention with the provisos that together A is not CH
2
; R
1
, R
2
, R
3
, R
4
, R
5
, R
6
, R
7
, R
10
, R
11
, R
12
and R
13
are not each H, R
8
is not Ph; and R
9
is not —OMe.
The compounds of the invention contain a chiral environment which is both rigid in structure and which, when complexed to a transition metal to form a catalyst, is located in close proximity to the metal reaction centre. Both of these features appear to account for the high asymmetric inductions observed by the inventors.
Having a —OMe group at position R
9
has been found to improve the selectivity of the compounds when used as catalysts. Furthermore, an aromatic group at R
8
in the case of compounds of Formula 1 and R
8
and R
14
in the case of Formula 2, has also been found to improve the selectivity of the compounds when used as catalysts.
Preferably the compound, according to Formula 1 the first aspect of the invention, has a formula according to Formula 3;
With respect to Formula 2, the groups on each side of linking group X are preferably identical, to facilitate easier production of the ligand compound.
Preferably the compounds of Formula 2 of the invention have a general Formula 4:
More preferably the compounds of this aspect of the invention have a formula according to Formula 5;
In use the compounds of the invention are chelated with at least one metal ion to form a catalytic compound. Accordingly a second aspect of the invention provides a catalytic compound comprising a compound according to the first aspect of the invention chelated to at least one transition metal ion.
Preferably the transition metal ion is selected from palladium, ruthenium, rhodium, tungsten, nickel, platinum, copper, cobalt, zinc and molybdenum. The complexation methods used are those known in the art.
A third aspect of the invention provides a chemical formulation or composition, comprising either a compound according to the first aspect of the invention or a catalyst according to the second aspect of the invention.
A fourth aspect of the invention provides a process for carrying out a chemical reaction comprising reacting reactants in the presence of a catalyst according to the second aspect of the invention. Preferably the chemical reaction is an organic asymmetric catalysis reaction.
The compounds and catalysts of the invention allow high levels of enantiomeric excess (e.e.) and percentage yield to be produced. Enantiomeric excess is defined as (% major enantiomer)−(% minor enantiomer). A compound of high enantiomeric excess preferably exhibits an enantiomeric excess of >80%, especially >90%. A compound of very high e.e. exhibits an e.e. of >95%.
Preferably the asymmetric catalysis reaction is asymmetric hydrogenation. This technique is demonstrated in, for example, the papers b

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