Asymmetric phosphine ligand

Details Asymmetric phosphine ligand Asymmetric phosphine ligand

2002-12-10

2004-05-04

Vollano, Jean F. (Department: 1621)

Catalyst, solid sorbent, or support therefor: product or process

Catalyst or precursor therefor

Organic compound containing

C556S021000, C568S012000, C568S017000

Reexamination Certificate

active

06730629

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a novel phosphine-phospholane compound, a production intermediate thereof, a transition metal complex containing the phosphine-phospholane compound as a ligand, a catalyst useful as a catalyst for various asymmetric syntheses, and catalytic asymmetric synthetic technology using the same. Furthermore, the invention relates to a novel optically active phosphine-phospholane compound, a production intermediate thereof, a transition metal complex containing the optically active phosphine-phospholane compound as a ligand, a catalyst useful as a catalyst for various asymmetric syntheses, and catalytic asymmetric synthetic technology using the same.
BACKGROUND OF THE INVENTION
Hitherto, many reports have been made on transition metal complex catalysts capable of being utilized in catalytic asymmetric syntheses such as asymmetric hydrogenations, asymmetric transfer hydrogenation reductions, asymmetric hydrosilylations, asymmetric hydroborations, asymmetric hydroformylations, asymmetric isomerizations of olefins, and asymmetric Heck reactions. Particularly, it is reported that complexes of transition metals such as ruthenium, iridium, rhodium, palladium, and nickel containing various optically active phosphines as ligands exhibit excellent performance as catalysts for asymmetric syntheses, and some of the catalysts are industrially employed (Asymmetric Catalysis in Organic Synthesis, Ed., R Noyori, Wiley & Sons, New York (1994)). Among these ligands, phospholane-type ligands are disclosed and transition metal complexes containing the ligands are reported to be useful as catalysts for catalytic asymmetric syntheses such as asymmetric hydrogenations ((1) H. Burunner, R. Sievi, J. Organometal. Chem., 1987, 328, 71; (2) WO 91/17998 (BPE); (3) WO 93/01199 (DuPHOS); (4) J. Org. Chem., 1998, 63, 8031 (RoPHOS); (5) WO 00/11008; (6) WO 99/59721 (PennPhos) (7) WO 00/26220; and so forth).
However, all the phospholane-type ligands disclosed in (1) to (6) contain two optically active phospholane rings per one molecule, so that their preparation requires a large amount of expensive optically active 1,3- or 1,4-diols. Moreover, in the synthesis of the diphosphine disclosed in (7), it is necessary to introduce an optically active center onto a phosphorus atom, which is difficult to synthesize. Thus, these ligands are not suitable for practical use.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a novel phosphine compound which can be synthesized from a small amount of an optically active compound and has excellent properties (chemical selectivity, enantioselectivity, catalytic activity) as a catalyst for asymmetric syntheses, especially asymmetric hydrogenations.
As a result of intensive studies for solving the above problem, the present inventors have found that a transition metal complex of an optically active phosphine-phospholane having a specific structure is effective for asymmetric hydrogenations.
Moreover, they have found that the transition metal complex exhibits excellent catalytic activity and enantio- or diastereo-selectivity in asymmetric hydrogenations of olefins such as enamides and &bgr;-monosubstituted dehydroamino acid derivatives, and accomplished the invention.
Incidentally, a ligand containing one optically active phospholane ring per one molecule has been reported in “Tetrahedron; Asymmetry 2001, 12, 1159”, which discloses the compound and process for producing the same but does not describe the preparation of a complex from a transition metal and the compound or asymmetric hydrogenation of a substrate in the presence of the complex, still less a compound having a substituent other than phenyl group on the phosphine and a process for producing the same.
DETAILED DESCRIPTION OF THE INVENTION
The following will explain the invention in detail.
The phosphine-phospholane compound of the invention is represented by the general formula (1):
(wherein R
1
represents hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms; R
2
represents hydrogen atom or OR
21
, where R
21
represents an alkyl group having 1 to 4 carbon atoms, a represents an integer of 1 to 2, b represents an integer of 1 to 3, the sum of a and b represents an integer of 2 to 3, provided that at least one of R
1
and R
2
is not a hydrogen atom; R
3
, R
4
, R
5
and R
6
are the same or different, and each represents hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, and each of R
3
and R
4
, R
4
and R
5
, and R
5
and R
6
may be combined together to form a ring which may contain one or more (preferably 1 to 2) oxygen atoms; and R
7
and R
8
are the same or different, and each represents (1) a linear or branched alkyl group having 1 to 6 carbon atoms, (2) a cycloalkyl group having 3 to 7 carbon atoms, (3) a perfluoroalkyl group, (4) a phenyl group, (5) a phenyl group having one or more (preferably 1 to 5) substituents each selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an alkyl group having 1 to 6 carbon atoms which is substituted by one or more (preferably 1 to 5) halogen atoms, an alkoxy group having 1 to 6 carbon atoms, and a halogen atom, (6) an aralkyl group having 7 to 12 carbon atoms, or (7) a ring-substituted aralkyl group).
The alkyl group having 1 to 4 carbon atoms for the above R
1
is selected from the group consisting of a methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, sec-butyl group, and tert-butyl group.
The alkyl group having 1 to 4 carbon atoms for the above R
21
is selected from the group consisting of a methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, sec-butyl group, and tert-butyl group.
The alkyl group having 1 to 6 carbon atoms for R
3
, R
4
, R
5
or R
6
is selected from the group consisting of a methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, iso-pentyl group, neo-pentyl group, tert-pentyl group, 2-methylpentyl group, n-hexyl group, and iso-hexyl group, and the alkoxy group having 1 to 6 carbon atoms includes a methoxy group, ethoxy group, n-propyloxy group, iso-propyloxy group, n-butoxy group, iso-butoxy group, sec-butoxy group, tert-butoxy group, n-pentyloxy group, iso-pentyloxy group, neo-pentyloxy group, tert-pentyloxy group, 2-methylpentyloxy group, n-hexyloxy group, and iso-hexyloxy group.
Furthermore, each of (1) R
3
and R
4
, (2) R
4
and R
5
, and (3) R
5
and R
6
may be together combined to form a ring, where the ring is preferably a ring having 5 to 10 carbon atoms, which is formed together with other carbon atoms. The ring may contain one or more (preferably 1 to 2) oxygen atoms. And the ring may have one or more (preferably 1 to 5) substituents.
Specific examples of a ring containing one or more (preferably 1 to 2) oxygen atoms include methylenedioxy group, ethylenedioxy group, or propylenedioxy group, and of a ring having 5 to 10 carbon atoms includes benzene, indane, tetrahydronaphthalene, indene, dihydronaphthalene, fluorene, naphthalene, anthracene, phenanthrene, and the like. The substituent for the rings includes an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 atoms, an alkyl group having 1 to 6 carbon atoms substituted by one or more (preferably 1 to 5) halogen atoms, a halogen atom, amino group, an amino group substituted by one or more (preferably 1 to 5) alkyl groups, and the like. The alkyl group having 1 to 6 carbon atoms and the alkoxy group having 1 to 6 atoms are selected from those described above.
The linear or branched alkyl group having 1 to 6 carbon atoms for the above R
7
or R
8
is selected from the same groups as described above. The cycloalkyl group having 3 to 7 carbon atoms is preferably a cyclopropyl group, methylcyclopropyl group, cyclobutyl group, cyclopentyl group, 2-methylcyclopentyl group, 3-methylcyclopentyl group, cyclohexyl group, 2-methylcyclohexy

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