SAINT-DIZIER ALEXANDRE CHRISTIAN (CH)
| WO2005105819A1 | 2005-11-10 | |||
| WO2005105819A1 | 2005-11-10 |
BARATTA W ET AL: "2-(AMINOMETHYL)PYRIDINE-PHOSPHINE RUTHENIUM(II) COMPLEXES: NOVEL HIGHLY ACTIVE TRANSFER HYDROGENATION CATALYSTS", ORGANOMETALLICS, ACS, WASHINGTON, DC, US, vol. 24, no. 7, 26 February 2005 (2005-02-26), pages 1660 - 1669, XP001236745, ISSN: 0276-7333, DOI: 10.1021/OM0491701
CRABTREE ET AL., ORGANOMETALLICS, vol. 30, 2011, pages 4174 - 4179
BARATTA ET AL., ORGANOMETALLICS, vol. 24, 2005, pages 1660 - 1669
CLARKE ET AL., DALTON TRANS., vol. 41, 2012, pages 10136
CAULTON ET AL., J. AM. CHEM. SOC., 1975, pages 4221 - 4228
ALBERS, INORG. SYNTH., vol. 26, 1989, pages 68 - 77
ALBERS, INORG. SYNTH, vol. 26, 1989, pages 249 - 258
CASTELLANO, INORG. CHIM. ACTA., vol. 363, 2009, pages 283 - 287
RIANT, CHEM. EUR. J., vol. 15, 2009, pages 6267 - 6268
| What is claimed is: 1 . A process for the preparation of a compound of formula I wherein X is -CH2-, -CH2-CH2-, -CH2-CH2-CH2- or -CH2-CH2-CH2-CH2-; Yi is -CH2-; -CH2-CH2- or -NH-; Y2 is NHR7 or SH ; wherein R7 is hydrogen, CrC4alkyl or phenyl; Ri and R2, independently from each other, represent aliphatic or aromatic groups; R3 and R4, independently from each other, represent aliphatic or aromatic groups; R5 and R6 are each hydrogen or together represent with the carbon atoms to which they are bonded, a phenyl ring; which process comprises reacting a compound of formula II [RuCI2(R8)n]m (II), wherein n is 1 and m is > 1 which represents a polymeric structure if R8 is a molecule containing two alkene or alkyne moieties coordinating in an hapto-2 coordination mode to the metal; or n is 4 and m is 1 if R8 is a nitrogen, oxygen or sulfur containing molecule in which said nitrogen, oxygen or sulfur coordinate to the metal; in the presence of an inert solvent which boiling point is from 1 12°C to 165°C with a compound of formula III wherein R5, R6, Yi and Y2 are as defined under formula I , and a phosphane of formula IV wherein R-i , R2, R3, R4 and X are as defined under formula I . 2. A process according to claim 1 for the preparation of compounds of formula I, wherein X is -CH2-CH2-CH2-CH2-. 3. A process according to claim 2 for the preparation of compounds of formula I , wherein R8 is cyclooctadiene or bicyclo[2.2.1 ]hepta-2,5-diene if n is 1 and m >1 ; or is dimethylsulfoxide if n is 4 and m is 1. 4. A process according to claim 2 for the preparation of compounds of formula I , wherein Ri , R2, R3 and R4 are phenyl and R5 and R6 are hydrogen or together represent with the carbon atoms to which they are bonded, a phenyl ring; Y2 is NH2. 5. A process according to claim 1 , wherein the compound of formula III is represented by compounds from the group consisting of the formulae 6. A process according to claim 1 performed as a one pot procedure. 7. A process according to claim 1 for the preparation of the compound of formula la wherein X is -CH2-, -CH2-CH2-, -CH2-CH2-CH2- or -CH2-CH2-CH2-CH2-; Yi is -CH2-; -CH2-CH2- or -NH-; Y2 is NHR7 or SH ; wherein R7 is hydrogen, CrC4alkyl or phenyl; Ri and R2, independently from each other, represent aliphatic or aromatic groups; R3 and R4, independently from each other, represent aliphatic or aromatic groups; and R5 and R6 are each hydrogen or together represent with the carbon atoms to which they are bonded, a phenyl ring; prepared by the process according to claim 1. 9. The compound of formula lb |
The present invention relates to a process for the diastereoselective preparation of ruthenium complexes and their use as catalysts in the hydrogenation of C=N and C=0 double bonds and in the oxidative synthesis of amides or esters. It is known that the cis-form of certain ruthenium(ll) complexes, for example RuCl 2 [PPh 2 (CH 2 ) 4 PPh 2 ][2-(H 2 NCH 2 )C 5 H4N] of formula la
are useful as a highly active hydrogenation catalysts. Said complex, its preparation and use as catalyst is described, for example, in WO 2005/105819 and in Crabtree et al. Organometallics 2011 , 30, 4174-4179. The catalyst can either adopt a cis or a trans configuration with respect to the chloro ligands.The cis-form of this complex is especially preferred since it shows much higher reactivity in the above mentioned hydrogenation reactions (Baratta et al., Organometallics 2005, 24, 1660-1669). It is therefore highly desired to selectively prepare the cis-form of said complex.
Clarke and co-workers report a procedure delivering structurally related complexes by consecutive addition of the ligands to the precursor [RuCI2(Py)2(NBD)] in methyl-THF (Clarke et al. Dalton Trans. 2012, 41 , 10136). However, the boiling point of methyl-THF is not sufficiently high to allow the formation of the highly active cis-complexes (the steric rearrangement needs high reaction temperatures e.g. boiling toluene). Another significant disadvantage of their procedure is the used catalyst precursor which is highly expensive and not available on an industrial scale. Further, the procedure reported by Clarke and coworkers includes the generation of two equivalents of toxic pyridine.
The synthesis of the compound of formula la according to WO 2005/105819, Crabtree et al. Organometallics 2011 , 30, 4174-4179 and Baratta et al., Organometallics 2005, 24, 1660- 1669 is based on a two step procedure. Further, long reaction times (20 hours) are described in preparatory examples 5 and 6 of WO 2005/105819. Moreover, all these procedures start from a catalyst precursor containing triphenlyphosphine as ligand. Said catalyst precursor has the formula RuCI 2 (PPh 3 )n (with n= 3.0, 3.1 , 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9 and 4.0) (Caulton et al., J. Am. C em. Soc. 1975, 4221 -4228). It can be derived from the formula of said catalyst precursor that it contains a large amount of triphenlyphosphine ligand that has to be exchanged in the next step. From an economical and environmental point of view this exchange is highly problematic as at least three equivalents of phosphorous waste are generated per equivalent of catalyst. The aim of the present invention is therefore to provide a novel, robust process for the diastereoselective production of the cis-form of RuCI 2 complexes of formula I in high yields and good quality in an economically advantageous way.
Thus, according to the present invention, there is provided a process for the preparation of a compound of formula I
wherein
X is -CH2-, -CH2-CH2-, -CH2-CH2-CH2- or -CH2-CH2-CH2-CH2-;
Yi is -CH2-; -CH2-CH2- or -NH-;
Y 2 is NHR 7 or SH; wherein R 7 is hydrogen, CrC 4 alkyl or phenyl;
Ri and R 2 , independently from each other, represent aliphatic or aromatic groups;
R 3 and R 4 , independently from each other, represent aliphatic or aromatic groups;
R 5 and R 6 are each hydrogen or together represent with the carbon atoms to which they are bonded, a phenyl ring; which process comprises reacting a compound of formula II
[RuCI 2 (R 8 )n]m (II) wherein n is 1 and m is > 1 which represents a polymeric structure if R 8 is a molecule containing two alkene or alkyne moieties coordinating in an hapto-2 coordination mode to the metal;
or n is 4 and m is 1 if R 8 is a nitrogen, oxygen or sulfur containing molecule in which said nitrogen, oxygen or sulfur coordinate to the metal;
in the presence of an inert solvent which boiling point is from 1 12°C to 165°C with a compound of formula III
wherein R 5 , R 6 , Yi and Y 2 are as defined under formula I, and a phosphane of formula IV wherein R-i , R 2 , R 3 , R 4 and X are as defined under formula I.
In a preferred embodiment of the invention,
X is preferably -CH 2 -CH 2 -CH 2 -CH 2 -.
In said preferred embodiment of the invention,
R 8 is preferably cis,cis-cycloocta-1 ,5 diene (cyclooctadiene or abbreviated as COD) or bicyclo[2.2.1 ]hepta-2,5-diene (norbornadiene or abbreviated as NBD) if n is 1 and m >1 ; or is preferably dimethylsulfoxide resulting in RuCI 2 (dmso-KORuCI 2 (dmso-KS) 3 (dmso-KO) or RuCI 2 (dmso-KS) 4 as precursors if n is 4 and m is 1 , but in particular cis,cis-cycloocta-1 ,5 diene or bicyclo[2.2.1]hepta-2,5-diene.
In said preferred embodiment of the invention,
Ri , R2, R3 and R 4 are preferably phenyl and
R 5 and R 6 are preferably hydrogen or together represent with the carbon atoms to which they are bonded, a phenyl ring;
Yi is preferably -CH 2 -, and
Y 2 is preferably NH 2 . The boiling point of the inert solvent according to the process of the invention is given at an atmospheric pressure of 1023.25 hPa. To achieve economically favourable reaction times, the reaction is performed at temperatures above 1 12°C (temperature at a pressure of 1023.25 hPa). Preferred inert solvents are ketones, preferably cyclohexanone, esters, preferably ethyl butyrate and aromatic solvents or mixtures of aromatic solvents with a boiling point from 1 12°C to 165°C (temperature at a pressure of 1023.25 hPa), preferably xylene and halogenated aromatic compounds preferably chlorobenzene. In said preferred embodiment of the invention, the inert solvent is preferably cyclohexanone, ethyl butyrate, xylene or chlorobenzene.
Preferred compounds of formula III for the process according to the invention are selected from the group consisting of the formulae
wherein the radicals signifiy methyl groups. The use of said preferred compounds of formula 111-1 to 111-10 are also especially preferred in said preferred embodiment of the invention mentioned above.
A preferred embodiment of the process according to the invention is characterized by reacting a compound of formula I la
[RuCI 2 (COD)]m (Ma), wherein ( m is >1 );
with 1 .225 equivalents of a bidentate amine ligand preferably 2-picolylamine or the compound (III-2) in presence of 1 equivalent of a bidentate phosphine ligand preferably 1 ,4- bis(diphenylphosphino)butane in an inert solvent like cyclohexanone at a reaction temperature from 125 to 135°C.
The process according to the present invention is especially useful for the preparation of catalysts of the formulae la and lb
The catalyst of the formula lb is novel and represent a further object of the invention. The catalyst of the formula lb crystallize more rapidly during subsequent purification; thereby enabeling faster filtration times and lower residual catalyst in the substrate solution. This is in particular of importance for the large scale production of the catalyst.
The process is preferably performed as an one pot procedure. An advantage of the one pot procedure in particular for large-scale manufacturing are significantly reduced reaction times. In addition, phosphane containing waste is remarkably reduced compared to the prior art process described in WO 2005/105819.
The synthesis of the precursors can be accomplished by a person skilled in the art following the procedures described in Albers et. al. Inorg. Synth. 1989, 26, 68-77 for RuCI 2 (cyclooctanediene) and Albers et. al. Inorg. Synth 1989, 26, 249-258 for RuCI 2 (bicyclo[2.2.1 ]hepta-2,5-diene) or Castellano et. al. Inorg. Chim. Acta. 2009, 363, 283- 287 for [RuCI 2 (dmso-KS) 3 (dmso-KO)] as well as Riant et. al. Chem. Eur. J. 2009, 15, 6267- 6268) for RuCI 2 (dmso-KS) 4 .
The catalyst precursors RuCI 2 (cyclooctanediene) and RuCI 2 (bicyclo[2.2.1]hepta-2,5-diene) show polymeric structures (illustrated by the definition m>1 ). In these cases the molecular formulae are more exactly represented by [RuCI 2 (cyclooctanediene)] m and [RuCI 2 (bicyclo[2.2.1]hepta-2,5-diene)] m . with m>1. This fact is also described in the above mentioned literature citations.
Preferably precursors with highest metal content and purities are used
- typically 29-37 weight-% ruthenium for [RuCI 2 (cyclooctanediene)] m ,
31 -39 weight-% ruthenium for [RuCI 2 (bicyclo[2.2.1]hepta-2,5-diene] m and 16-21 weight-% ruthenium for [RuCI 2 (dmso-KS)3(dmso-KO)] and for RuCI 2 (dmso-KS) 4 .
The efficiency of the catalysts of formula la made from [RuCI 2 (COD)] m as the precursor is equivalent to that of the catalyst of formula la made from [RuCI 2 (PPh 3 ) n ] as the precursor for both reduction under hydrogen atmosphere and transfer hydrogenation.
Table 1 Catalytic reduction of acetophenone to 1 -phenylethanol under hydrogen atmosphere in the presence of ruthenium complexes
Pre-catalyst Molar ratio Pressure Conversion Reaction Time
Acetophenone/Ru/Base bar % min
[RuCI 2 (PPh 3 ) n ] 4000/1/85 9 99 225
[RuCI 2 (COD)] m 4000/1/85 9 99 225
Table 2 Catalytic reduction of acetophenone to 1 -phenylethanol in the presence of ruthenium complexes
Pre-catalyst Molar ratio Conversion Reaction Time
Acetophenone/Ru/Base % min
[RuCI 2 (PPh 3 ) n ] 4000/1/85 98 30
[RuCI 2 (COD)] m 4000/1/85 94 60 Preparatory examples:
Example P1 : Preparation of RuCI 2 [PPh 2 (CH 2 ) 4 PPh 2 ][2-H 2 NCH 2 )C 5 H 4 N] of formula la
The catalyst precursor, preferably [RuCI 2 (COD)]m (1 eq.) (COD = cis,cis-cycloocta-1 ,5 diene), 1 ,4-bis(diphenylphosphino)butane (1.0-1 .2 eq., preferably 1.0 eq.) and 2-picolylamine (1 .0-1.4 eq., preferably 1.225 eq.) were dissolved in one of the above mentioned solvents, preferably methyl isobutylketone (10-20 ml/g Ru-precursor, preferably 20 ml/g). The mixture was heated to reflux for 3 - 5 hours and then cooled to ambient temperature. The solid precipitate was filtered off and washed with the same solvent that was used for the reaction. A person skilled in the art can determine the cis-/trans- isomeric ratio by NMR. The diastereomeric ratios generated by this method are usually in the range of d.r. (diastereomeric ratio) >98% towards the cis isomer. The same results can be achieved starting with [RuCI 2 (dmso-KS)3(dmso-KO)], [RuCI 2 (dmso-KS) 4 ]or [RuCI 2 (bicyclo[2.2.1 ]hepta- 2,5-diene)] m as precursor. Example P2: Preparation of RuCI 2 [PPh 2 (CH 2 ) 4 PPh 2 ][2-H 2 NCH 2 )C 9 H 6 N] of formula lb
The catalyst precursor, preferably [RuCI 2 (COD)]m (1 eq.), 1 ,4-bis(diphenylphosphino)butane (1 .0-1 .2 eq., preferably 1 .0 eq.) and 2- quinolinylmethylamine (1.0-1 .4 eq., preferably 1.225 eq.) were dissolved in one of the above mentioned solvents, preferably cyclohexanone (10- 20 ml/g Ru-precursor, preferably 20 ml/g). The mixture was heated at 130 °C for 1 hour and then cooled to ambient temperature. The solid precipitate was filtered off and washed with the same solvent that was used for the reaction. A person skilled in the art can determine the cis-/trans- isomeric ratio by NMR. The diastereomeric ratios generated by this method are usually in the range of d.r. (diastereomeric ratio) >98% towards the cis isomer. The same results can be achieved starting with [RuCI 2 (dmso-KS)3(dmso-KO)], [RuCI 2 (dmso-KS) 4 ]or [RuCI 2 (bicyclo[2.2.1]hepta-2,5-diene)] m as precursor.