N-substituted pyridiniophosphines, processes for their preparation and their use
The present invention deals with the synthesis and applications of new cationic compounds being useful as metal ligands. Specifically, N-alkyl/aryl substituted pyridiniophosphines are prepared and used as ligands for transition metals. The so-obtained metal complexes and their use as catalysts in chemical synthesis is also described. It also worth mentioning that N-alkyl/aryl pyridiniophosphines can be synthesized through a short, scalable and highly modular route.
1. N-substituted pyridiniophosphine of the general formula (I):
wherein
R 1 , R 2 , R 3 and R 4 are identical or different and each represent hydrogen, halogen, a linear, cyclic or branched C 1 -C 20 -alkyl, -alkenyl group or -alkynyl group or C 5 -C 14 -aryl or -heteroaryl group, which can have suitable substituents selected from halogen, ═O, —OH, —OR, —NH 2 , —NHR, —NR 2 , aryl or heteroaryl, or at least one of R 1 , R 2 , R 3 and R 4 is bound to the pyridinio ring via —O— or —NR—, or at least two of R 1 , R 2 , R 3 and R 4 can form a linear or branched C 4 to C 12 alkyl ring, which can comprise at least one unsaturated bond and which can have suitable substituents selected from halogen, ═O, —OH, —OR, —NH 2 , —NHR, —NR 2 , aryl or heteroaryl, or at least two of R 1 , R 2 , R 3 and R 4 can form a C 5 to C 14 -aromatic or -heteroaromatic ring which can have suitable substituents selected from halogen, —OH, —OR, —NH 2 , —NHR, —NR 2 , aryl or heteroaryl;
R 5 represents a linear, cyclic or branched C 1 -C 20 -alkyl group or C 5 -C 14 -aryl or -heteroaryl group, which can have suitable substituents selected from halogen, ═O, —OH, —OR, —NH 2 , —NHR, —NR 2 , aryl or heteroaryl;
R 6 and R 7 each represent a saturated or unsaturated, linear, branched or cyclic C 1 -C 20 -alkyl group or or C 5 -C 14 -aryl or -heteroaryl group, which can have suitable substituents selected from halogen, —OH, —OR, —NH 2 , —NHR, —NR 2 , aryl or heteroaryl, or R 6 and R 7 can form a C 4 to C 20 ring which can comprise at least one unsaturated bond or an aromatic or heteroaromatic ring which can have suitable substituents selected from halogen, —OH, —OR, —NH 2 , —NHR, —NR 2 , aryl or heteroaryl,
R represents a C 1 -C 20 -alkyl group or C 5 -C 14 -aryl or -heteroaryl group which can have suitable substituents selected from halogen, ═O, —OH, —OR, —NH 2 , —NHR, —NR 2 , aryl or heteroaryl, and
X − is an anion.
2. N-substituted pyridiniophosphine of the general formula (I) according to claim 1 , wherein R 1 , R 3 and R 4 each represent hydrogen and R 2 represents halogen, a linear, cyclic or branched C 1 -C 20 -alkyl, -alkenyl or -alkynyl group or C 5 -C 14 -aryl or -heteroaryl group, which can have suitable substituents selected from halogen, ═O, —OH, —OR, —NH 2 , —NHR, —NR 2 , aryl or R 2 is bound to the pyridinio ring via —O— or —NR—; and
R 5 , R 6 , R 7 , R and X − have the meaning as given in claim 1 .
3. N-substituted pyridiniophosphine of the general formula (I) according to claim 1 , wherein X − is an anion selected from Cl − , Br − , I − , PF 6 − , SbF 6 − , BF 4 − , ClO 4 − , F 3 CCOO − , Tf 2 N − , (Tf=trifluoromethanesulfonyl), TfO − , tosyl, [B[3,5-(CF 3 ) 2 C 6 H 3 ] 4 ] − , [B(C 6 F 5 ) 4 ] − , and [Al(OC(CF 3 ) 3 ) 4 ] − .
4. A process for the preparation of N-substituted pyridiniophosphine with the general formula I:
wherein
R 1 , R 2 , R 3 and R 4 are identical or different and each represent hydrogen, halogen, a linear, cyclic or branched C 1 -C 20 -alkyl, -alkenyl group or -alkynyl group or C 5 -C 14 -aryl or -heteroaryl group, which can have suitable substituents selected from halogen, ═O, —OH, —OR, —NH 2 , —NHR, —NR 2 , aryl or heteroaryl, or at least one of R 2 , R 3 and R 4 is bound to the pyridinio ring via —O— or —NR—, or at least two of R 1 , R 2 , R 3 and R 4 can form a linear or branched C 4 -C 12 -alkyl ring, which can comprise at least one unsaturated bond and which can have suitable substituents selected from halogen, ═O, —OH, —OR, —NH 2 , —NHR, —NR 2 , aryl or heteroaryl, or at least two of R 1 , R 2 , R 3 and R 4 can form a C 5 -C 14 -aromatic or -heteroaromatic ring which can have suitable substituents selected from halogen, —OH, —OR, —NH 2 , —NHR, —NR 2 , aryl or heteroaryl;
R 5 represents a linear, cyclic or branched C 1 -C 20 -alkyl group or C 5 -C 14 -aryl or -heteroaryl group, which can have suitable substituents selected from halogen, ═O, —OH, —OR, —NH 2 , —NHR, —NR 2 , aryl or heteroaryl;
R 6 and R 7 each represent a saturated or unsaturated, linear, branched or cyclic C 1 -C 20 -alkyl group or C 5 -C 14 -aryl or -heteroaryl group, which can have suitable substituents selected from halogen, —OH, —OR, —NH 2 , —NHR, —NR 2 , aryl or heteroaryl, or R 6 and R 7 can form a C 4 to C 20 ring which can comprise at least one unsaturated bond or an aromatic or heteroaromatic ring which can have suitable substituents selected from halogen, —OH, —OR, —NH 2 , —NHR, —NR 2 , aryl or heteroaryl;
R represents a C 1 -C 20 -alkyl group or C 5 -C 14 -aryl or -heteroaryl group which can have suitable substituents selected from halogen, ═O, —OH, —OR, —NH 2 , —NHR, —NR 2 , aryl or heteroaryl, and
X − is an anion,
in which process a pyridinio-compound salt with the general formula II:
wherein R 1 , R 2 , R 3 , R 4 , R 5 and X − are defined as above and Q represents a leaving group,
is reacted with a phosphine of the general formula III:
HPR 6 R 7 (III)
in which R 6 and R7 are defined as above.
5. A metal complex comprising as a ligand a N-substituted pyridiniophosphine of the general formula (I) according to claim 1 .
6. Metal complex of the general formula (IV)
wherein
R 1 , R 2 , R 3 and R 4 are identical or different and each represent hydrogen, halogen, a linear, cyclic or branched C 1 -C 20 -alkyl, -alkenyl group or -alkynyl group or C 5 -C 14 -aryl or -heteroaryl group, which can have suitable substituents selected from halogen, ═O, —OH, —OR, —NH 2 , —NHR, —NR 2 , aryl or heteroaryl, or at least one of R 1 , R 2 , R 3 and R 4 is bound to the pyridinio ring via —O— or —NR—, or at least two of R 1 , R 2 , R 3 and R 4 can form a linear or branched C 4 -C 12 -alkyl ring, which can comprise at least one unsaturated bond and which can have suitable substituents selected from halogen, ═O, —OH, —OR, —NH 2 , —NHR, —NR 2 , aryl or heteroaryl, or at least two of R 1 , R 2 , R 3 and R 4 can form a C 5 -C 14 -aromatic or -heteroaromatic ring which can have suitable substituents selected from halogen, —OH, —OR, —NH 2 , —NHR, —NR 2 , aryl or heteroaryl;
R 5 represents a linear, cyclic or branched C 1 -C 20 -alkyl group or C 5 -C 14 -aryl or -heteroaryl group, which can have suitable substituents selected from halogen, ═O, —OH, —OR, —NH 2 , —NHR, —NR 2 , aryl or heteroaryl;
R 6 and R 7 each represent a saturated or unsaturated, linear, branched or cyclic C 1 -C 20 -alkyl group or C 5 -C 14 -aryl or -heteroaryl group, which can have suitable substituents selected from halogen, —OH, —OR, —NH 2 , —NHR, —NR 2 , aryl or heteroaryl; or R 6 and R 7 can form a C 4 to C 20 ring which can comprise at least one unsaturated bond or an aromatic or heteroaromatic ring which can have suitable substituents selected from halogen, —OH, —OR, —NH 2 , —NHR, —NR 2 , aryl or heteroaryl,
R represents a C 1 -C 20 -alkyl group or C 5 -C 14 -aryl or -heteroaryl group which can have suitable substituents selected from halogen, ═O, —OH, —OR, —NH 2 , —NHR, —NR 2 , aryl or heteroaryl, and
X − is an anion,
M represents a metal atom,
L represents a ligand which can be also cationic, neutral or anionic and can be the same or different if more than one L is coordinated to the metal, and
m can be 1, 2 or 3,
n can be 1, 2 or 3,
o can be an integer from 1 to 5, and
m, n and o are chosen, depending on the metal atom, to obtain a metal complex.
7. The metal complex as claimed in claim 6 , wherein the ligand L can be chosen from halogen, CN, CO, alkenes, cycloalkenes and/or alkynes, arenes, nitriles, phosphines, amines, pyridines or carboxylates.
8. The metal complex as claimed in claim 6 , wherein M is selected from Ag, Au, Ru, Rh, Pd, Os, Ir and Pt.
9. An organic synthesis process comprising conducting a chemical reaction in the presence of a catalyst, wherein the catalyst is the metal complex as claimed in claim 6 .
10. N-substituted pyridiniophosphine of the general formula (I) according to claim 1 , wherein heteroaryl is selected from among the groups 2- or 3-furyl, 2- or 3-thienyl, 1-, 2- or 3-pyrrolyl, 1-, 2-, 4- or 5-imidazolyl, 1-, 3-, 4- or 5-pyrazolyl, 2-, 4- or 5-oxazolyl, 3-, 4- or 5-isoxazolyl, 2-, 4- or 5-thiazolyl, 3-, 4- or 5-isothiazolyl, 2-, 3- or 4-pyridyl, 2-, 4-, 5- or 6-pyrimidinyl, 1,2,3-triazol-1-, -4- or -5-yl, 1,2,4-triazol-1-, -3- or -5-yl, 1- or 5-tetrazolyl, 1,2,3-oxadiazol-4- or -5-yl, 1,2,4-oxadiazol-3- or -5-yl, 1,3,4-thiadiazol-2- or -5-yl, 1,2,4-thiadiazol-3- or -5-yl, 1,2,3-thiadiazol-4- or -5-yl, 3- or 4-pyridazinyl, pyrazinyl, 1-, 2-, 3-, 4-, 5-, 6- or 7-indolyl, 4- or 5-isoindolyl, 1-, 2-, 4- or 5-benzimidazolyl, 1-, 3-, 4-, 5-, 6- or 7-benzopyrazolyl, 2-, 4-, 5-, 6- or 7-benzoxazolyl, 3-, 4-, 5-, 6- or 7-benzisoxazolyl, 2-, 4-, 5-, 6- or 7-benzothiazolyl, 2-, 4-, 5-, 6- or 7-benzisothiazolyl, 4-, 5-, 6- or 7-benz-2,1,3-oxadiazolyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-quinolyl, 1-, 3-, 4-, 5-, 6-, 7- or 8-isoquinolyl, 3-, 4-, 5-, 6-, 7- or 8-cinnolinyl, 2-, 4-, 5-, 6-, 7- or 8-quinazolinyl, 5- or 6-quinoxalinyl, 2-, 3-, 5-, 6-, 7- or 8-2H-benzo-1,4-oxazinyl, 1,3-benzodioxol-5-yl, 1,4-benzodioxan-6-yl, 2,1,3-benzothiadiazol-4- or -5-yl or 2,1,3-benzoxadiazol-5-yl, each of which heteroaryl groups is optionally substituted as provided in claim 1 .