Transfer hydrogenation process

Details Transfer hydrogenation process Transfer hydrogenation process

2001-03-21

2003-01-21

Davis, Brian J. (Department: 1621)

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

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C546S144000, C546S148000, C546S150000, C548S469000, C548S490000, C564S248000, C564S269000, C564S271000, C564S272000, C564S273000, C564S274000, C564S275000, C564S278000, C564S279000

Reexamination Certificate

active

06509467

ABSTRACT:

This invention relates to catalytic transfer hydrogenation, particularly in the presence of a complexed transition metal, and to a process of making optically active compounds.
According to a first aspect of the present invention there is provided a process for the transfer hydrogenation of a compound of formula (1)
wherein:
X represents (NR
3
R
4
)
+
Q
−
, N
+
R
5
—O
31
, (NR
6
OR
7
)
+
Q
−
, (NR
8
NR
9
R
10
)
+
Q
31
, (NR
8
NR
9
C(═NR
11
)R
12
)
+
Q
−
, (NR
8
NR
9
SO
2
R
13
)
+
Q
−
, or (NR
8
NR
9
COR
14
)
+
Q
−
;
Q
−
represents a monovalent anion;
R
1
, R
2
, R
3
, R
4
, R
5
, R
6
, R
7
, R
8
, R
9
, R
10
, and R
11
each independently represents a hydrogen atom, an optionally substituted hydrocarbyl, a perhalogenated hydrocarbyl or an optionally substituted heterocyclyl group, one or more of R
1
& R
2
, R
1
& R
3
, R
2
& R
4
, R
3
& R
4
, R
1
& R
5
, R
1
& R
6
, R
2
& R
7
, R
1
& R
8
, R
1
& R
9
, R
6
& R
7
, R
8
& R
9
and R
9
& R
10
optionally being linked in such a way as to form an optionally substituted ring(s); and
R
12
, R
13
and R
14
each independently represents an optionally substituted hydrocarbyl, a perhalogenated hydrocarbyl or an optionally substituted heterocyclyl group;
said process comprising reacting the compound of formula (1) with a hydrogen donor in the presence of a catalyst, characterised in that the catalyst has the general formula:
wherein:
R
15
represents a neutral optionally substituted hydrocarbyl or perhalogenated hydrocarbyl ligand;
A represents —NR
16
—, —NR
17
—, —NHR
16
, —NR
16
R
17
or —NR
17
R
18
where R
16
is H, C(O)R
18
, SO
2
R
18
, C(O)NR
18
R
22
, C(S)NR
18
R
22
, C(═NR
22
)SR
23
or C(═NR
22
)OR
23
, R
17
and R
18
each independently represents an optionally substituted hydrocarbyl, perhalogenated hydrocarbyl or an optionally substituted heterocyclyl group, and R
22
and R
23
are each independently hydrogen or a group as defined for R
18
;
B represents —O—, —OH, OR
19
, —S—, —SH, SR
19
, —NR
19
—, —NR
20
—, —NHR
20
, —NR
19
R
20
, —NR
19
R
21
, —PR
19
— or —PR
19
R
21
where R
20
is H, C(O)R
21
, SO
2
R
21
, C(O)NR
21
R
24
, C(S)NR
21
R
24
, C(═NR
24
)SR
25
or C(═NR
24
)OR
25
, R
19
and R
21
each independently represents an optionally substituted hydrocarbyl, perhalogenated hydrocarbyl or an optionally substituted heterocyclyl group, and R
24
and R
25
are each independently hydrogen or a group as defined for R
21
;
E represents a linking group;
M represents a metal capable of catalysing transfer hydrogenation; and
Y represents an anionic group, a basic ligand or a vacant site;
provided that when Y is not a vacant site that at least one of A or B carries a hydrogen atom.
The catalytic species is believed to be substantially as represented in the above formula. It may be introduced on a solid support.
When X represents (NR
3
R
4
)
+
Q
31
, compounds of formula (1) are iminium salts. Iminium salts include protonated imine salts and quaternary imine salts, preferably quaternary imine salts. Quaternary imine salts are represented by compounds of formula (1) in which both R
3
and R
4
are not hydrogen.
Anions which may be represented by Q
−
include halides, optionally substituted arylsulphonates, such as optionally substituted phenyl and napthyl sulphonates, optionally substituted alkylsulphonates including halogenated alkylsulphonates, such as C
1-20
alkylsulphonates, optionally substituted carboxylates, such as C
1-10
alkyl and aryl carboxylates, ions derived from the polyhalogenation of boron, phosphorous or antimony, and other common inorganic ions for example perchlorate. Examples of anions which may be present are bromide, chloride, iodide, hydrogen sulphate, tosylate, formate, acetate, tetrafluoroborate, hexafluorophosphate, hexafluoroantimonate, perchlorate, trifluoromethanesulphonate and trifluoroacetate. Preferred anions include bromide, chloride, iodide, formate and trifluoroacetate, particularly preferred anions include iodide, formate and trifluoroacetate.
Hydrocarbyl groups which may be represented by R
1-14
, R
17
, R
18
, R
19
and R
21-25
independently include alkyl, alkenyl and aryl groups, and any combination thereof, such as aralkyl and alkaryl, for example benzyl groups.
Alkyl groups which may be represented by R
1-14
, R
17
, R
18
, R
19
and R
21-25
include linear and branched alkyl groups comprising up to 20 carbon atoms, particularly from 1 to 7 carbon atoms and preferably from 1 to 5 carbon atoms. When the alkyl groups are branched, the groups often comprise up to 10 branched chain carbon atoms, preferably up to 4 branched chain atoms. In certain embodiments, the alkyl group may be cyclic, commonly comprising from 3 to 10 carbon atoms in the largest ring and optionally featuring one or more bridging rings. Examples of alkyl groups which may be represented by R
1-14
, R
17
, R
18
, R
19
and R
21-25
include methyl, ethyl, propyl, 2-propyl, butyl, 2-butyl, t-butyl and cyclohexyl groups.
Alkenyl groups which may be represented by R
1-14
, R
17
, R
18
, R
19
and R
21-25
include C
2-20
, and preferably C
2-6
alkenyl groups. One or more carbon-carbon double bonds may be present. The alkenyl group may carry one or more substituents, particularly phenyl substituents. Examples of alkenyl groups include vinyl, styryl and indenyl groups. When either of R
1
or R
2
represents an alkenyl group, a carbon-carbon double bond is preferably located at the position &bgr; to the C═X moiety. When either of R
1
or R
2
represents an alkenyl group, the compound of formula (1) is preferably an &agr;,&bgr;-unsaturated iminium compound.
Aryl groups which may be represented by R
1-14
, R
17
, R
18
, R
19
and R
21-25
may contain 1 ring or 2 or more fused rings which may include cycloalkyl, aryl or heterocyclic rings. Examples of aryl groups which may be represented by R
1-14
, R
17
, R
18
, R
19
and R
21-25
include phenyl, tolyl, fluorophenyl, chlorophenyl, bromophenyl, trifluoromethylphenyl, anisyl, naphthyl and ferrocenyl groups.
Perhalogenated hydrocarbyl groups which may be represented by R
1-14
, R
17
, R
18
, R
19
and R
21-25
independently include perhalogenated alkyl and aryl groups, and any combination thereof, such as aralkyl and alkaryl groups. Examples of perhalogenated alkyl groups which may be represented by R
1-14
, R
17
, R
18
, R
19
and R
21-25
include —CF
3
and —C
2
F
5
.
Heterocyclic groups which may be represented by R
1-14
, R
17
, R
18
, R
19
and R
21-25
independently include aromatic, saturated and partially unsaturated ring systems and may constitute 1 ring or 2 or more fused rings which may include cycloalkyl, aryl or heterocyclic rings. The heterocyclic group will contain at least one heterocyclic ring, the largest of which will commonly comprise from 3 to 7 ring atoms in which at least one atom is carbon and at least one atom is any of N, O, S or P. When either of R
1
or R
2
represents or comprises a heterocyclic group, the atom in R
1
or R
2
bonded to the C═X group is preferably a carbon atom. Examples of heterocyclic groups which may be represented by R
1-14
, R
17
, R
18
, R
19
and R
21-25
include pyridyl, pyrimidyl, pyrrolyl, thiophenyl, furanyl, indolyl, quinolyl, isoquinolyl, imidazoyl and triazoyl groups.
When any of R
1-14
, R
17
, R
18
, R
19
and R
21-25
is a substituted hydrocarbyl or heterocyclic group, the substituent(s) should be such so as not to adversely affect the rate or stereoselectivety of the reaction. Optional substituents include halogen, cyano, nitro, hydroxy, amino, thiol, acyl, hydrocarbyl, perhalogenated hydrocarbyl, heterocyclyl, hydrocarbyloxy, mono or di-hydrocarbylamino, hydrocarbylthio, esters, carbonates, amides, sulphonyl and sulphonamido groups wherein the hydrocarbyl groups are as defined for R
1
above. One or more substituents may be present.
When any of R
1
& R
2
, R
1
& R
3
, R
2
& R
4
, R
3
& R
4
, R
1
& R
5
, R
1
& R
6
, R
2
& R
7
, R
1
& R
8
, R
1
& R
9
, R
6
& R
7
, R
8
& R
9
and R
9

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