Hydrogenation of esters with ru/bidentate ligands complexes

Abstract

The present invention relates to the field of catalytic hydrogenation and, more particularly, to the use of Ru complexes with bidentate ligands, having one amino or imino coordinating group and one phosphino coordinating group, in hydrogenation processes for the reduction of esters or lactones into the corresponding alcohol or diol respectively.

1 . A process for the reduction by hydrogenation, using molecular H 2 , of a C 3 -C 70  substrate containing one or two ester or lactone functional groups into its corresponding alcohol or diol, which comprises carrying out the process in the presence of a base and at least one complex in the form of a ruthenium complex of formula
   [Ru(L2) b (L′) a Y 2 ]  (1)   wherein L2 represents a C 4 -C 40  bidentate ligand wherein the coordinating groups consist of one amino or imino group and one phosphino group;   L′ represents a C 3 -C 70  mono-phosphine or a molecule of solvent;   b is 1 and a is 1 or 2 or b is 2 and a is 0; and   each Y represents, simultaneously or independently, CO, a hydrogen or halogen atom, a hydroxyl group, a BH 4  or ALH 4  group or a C 1 -C 6  alkoxy or carboxylic radical.   
   
   
       2 . The process according to  claim 1 , wherein the amino group is a NH 2  or NH group. 
   
   
       3 . The process according to  claim 1 , wherein the ruthenium complex is of formula
   [Ru(L2) 2 Y 2 ]  (2)   wherein L2 and Y have the meaning indicated in  claim 1 .   
   
   
       4 . The process according to  claim 1 , wherein L2 is a compound of one of the formulae 
     
       
         
         
             
             
         
       
       wherein the dotted line indicates a single or double bond; 
       z is 0 or 1 when the carbon-nitrogen bond with the dotted line represents a single or double bond respectively; 
       R 1  represents a hydrogen atom, a linear, branched or cyclic C 1  to C 10  alkyl or alkenyl group optionally substituted; 
       R 1′  and R 1″ , when taken separately, represents a hydrogen atom, a linear, branched or cyclic C 1  to C 9  alkyl or alkenyl group optionally substituted or a C 6  to C 10  aromatic group optionally substituted; the R 1′  or R 1″ , when taken together, form a saturated or unsaturated ring optionally substituted, having 5 to 12 atoms and including the carbon atom to which the R 1′  and R 1″  groups are bonded; 
       R 2  and R 3 , when taken separately, represent, simultaneously or independently, a linear, branched or cyclic C 1  to C 8  alkyl or alkenyl group optionally substituted, a C 6  to C 10  aromatic group optionally substituted, or an OR 2′  or NR 2′ R 3′  group, R 2′  and R 3′  being a C 1  to C 8  alkyl or alkenyl group; or the groups R 2  and R 3 , when taken together, form a saturated or unsaturated ring optionally substituted, having 5 to 10 atoms and including the phosphorus atom to which the R 2  and R 3  groups are bonded; 
       R 6  and R 7  represent, simultaneously or independently, a hydrogen atom, a linear, branched or cyclic C 1  to C 10  alkyl or alkenyl group optionally substituted, a C 6 -C 10  aromatic group optionally substituted, or an OR 4′  or NR 4′ R 5′  group, R 4′  and R 5′  being a linear, branched or cyclic C 1  to C 10  alkyl or alkenyl group; R 6  and R 1  or R 6  and R 1″ , taken together, may form a saturated or unsaturated heterocycle, optionally substituted and optionally containing one or two additional nitrogen or oxygen atoms, containing 5 to 10 atoms and including the carbon atoms and the N atom to which the R 6  or R 1 , or R 1″ , group are bonded respectively; and 
       Q represents:
 a group of formula 
 
     
     
       
         
         
             
             
         
       
       
         wherein n is an integer from 1 to 4, and 
         R 4  and R 5  represent, simultaneously or independently, a hydrogen atom, a linear, branched or cyclic C 1  to C 10  alkyl or alkenyl group optionally substituted, a C 6 -C 10  aromatic group optionally substituted, or an OR 4′  or NR 4′ R 5′  group, R 4′  and R 5′  being a linear, branched or cyclic C 1  to C 10  alkyl or alkenyl group; two distinct R 4  and/or R 5  groups, taken together, may form a C 5  to C 10 , saturated ring optionally substituted, including the carbon atoms to which each of the R 4  or R 5  group is bonded; or 
         a group of formula 
       
     
     
       
         
         
             
             
         
       
       
         wherein n is an integer from 2 to 4, and 
         two distinct adjacent R 4  groups, taken together, form a C 5  to C 10 , aromatic ring optionally substituted or a C 5 -C 12  metallocenediyl optionally substituted, including the carbon atoms to which each of the R 4  group are bonded; or 
         three distinct adjacent R 4  groups, taken together, form a naphthalene ring optionally substituted, including the carbon atoms to which each of the R 4  groups are bonded; 
       
       and wherein the substituents of R 1′ , R 1″  and R 1  to R 7  and Q are one or two halogen, C 1  to C 10  alkoxy or polyalkyleneglycols groups, halo- or perhalo-hydrocarbon, COOR, NR 2 , quaternary amine or R groups, wherein R is a C 1  to C 6  alkyl, or a C 5  to C 12  cycloalkyl, aralkyl or aromatic group, the latter being also optionally substituted by one, two or three halogen, sulfonates groups or C 1 -C 8  alkyl, alkoxy, amino, nitro, sulfonates, halo- or perhalo-hydrocarbon or ester groups. 
     
   
   
       5 . The process according to  claim 1 , wherein L2 is a ligand of formula 
     
       
         
         
             
             
         
       
       in which R 1  represents a hydrogen atom, a linear, branched or cyclic C 1  to C 6  alkyl or alkenyl group optionally substituted; 
       R 2  and R 3  represent, simultaneously or independently, a linear, branched or cyclic C 1  to C 6  alkyl group optionally substituted, a phenyl or naphthyl group optionally substituted; or the groups R 2  and R 3 , taken together, form a saturated or unsaturated ring optionally substituted, having 5, 6 or 7 atoms and including the phosphorus atom to which the R 2  and R 3  groups are bonded; 
       R 6  and R 7  represent, simultaneously or independently, a hydrogen atom, a linear or branched C 1  to C 4  alkyl group optionally substituted, a phenyl ring optionally substituted; R 6  and R 1 , taken together, may form a saturated or unsaturated heterocycle, optionally substituted and optionally containing one additional nitrogen or oxygen atoms, containing 5 or 6 atoms and including the carbon atoms and the N atom to which the R 6  or R 1  group are bonded respectively; and 
       Q represents:
 a group of formula 
 
     
     
       
         
         
             
             
         
       
       
         wherein n is an integer from 2 or 3, and 
         R 4  and R 5  represent, simultaneously or independently, a hydrogen atom, a linear or branched C 1  to C 4  alkyl group optionally substituted, a phenyl ring optionally substituted; or two distinct R 4  and/or R 5  groups, taken together, form a C 5  to C 10  saturated ring optionally substituted including the carbon atoms to which each of the R 4  or R 5  group is bonded; or 
         a group of formula 
       
     
     
       
         
         
             
             
         
       
       
         wherein n is an integer from 1 to 3, and 
         two distinct adjacent R 4  groups, taken together, form a C 5  to C 10  aromatic ring optionally substituted or a C 5 -C 12  ferrocenediyl optionally substituted, including the carbon atoms to which each of the R 4  group are bonded; or 
         three distinct adjacent R 4  groups, taken together, form a naphthalene ring optionally substituted, including the carbon atoms to which each of the R 4  group are bonded. 
       
     
   
   
       6 . The process according to  claim 1 , wherein L2 is a ligand of formula (2-C) or (2-D) 
     
       
         
         
             
             
         
       
       wherein the dotted lines in formula (2-D) indicate the presence of a phenyl or a naphthyl group; 
       d represents 1 or 2; 
       R 1  represents a hydrogen atom or a C 1  to C 4  linear or branched alkyl group possibly substituted; 
       R 2  and R 3  represent a linear, branched or cyclic C 1  to C 6  alkyl group optionally substituted or an phenyl group optionally substituted; and 
       R 6  and R 7  represent, simultaneously or independently, a hydrogen atom, a linear or branched C 1  to C 4  alkyl group optionally substituted, or an phenyl group optionally substituted; or R 6  and R 1 , taken together, form a saturated heterocycle, optionally substituted and optionally containing an additional nitrogen or oxygen atoms. 
     
   
   
       7 . The process according to  claim 1 , wherein L2 is a ligand of formula 
     
       
         
         
             
             
         
       
       in which R 1  represents a hydrogen atom, a linear, branched or cyclic C 1  to C 6  alkyl or alkenyl group optionally substituted; 
       R 2  and R 3  represent, simultaneously or independently, a linear, branched or cyclic C 1  to C 6  alkyl group optionally substituted, a phenyl or naphthyl group optionally substituted; or the groups R 2  and R 3 , taken together, form a saturated or unsaturated ring optionally substituted, having 5, 6 or 7 atoms and including the phosphorus atom to which the R 2  and R 3  groups are bonded; 
       Q represents:
 a group of formula 
 
     
     
       
         
         
             
             
         
       
       
         wherein n is an integer from 2 or 3, and 
         R 4  and R 5  represent, simultaneously or independently, a hydrogen atom, a linear or branched C 1  to C 4  alkyl group optionally substituted, a phenyl ring optionally substituted; or two distinct R 4  and/or R 5  groups, taken together, form a C 5  to C 10  saturated ring optionally substituted including the carbon atoms to which each of the R 4  or R 5  group is bonded; or 
         a group of formula 
       
     
     
       
         
         
             
             
         
       
       
         wherein n is an integer from 1 to 3, and 
         two distinct adjacent R 4  groups, taken together, form a C 5  to C 10  aromatic ring optionally substituted or a C 5 -C 12  ferrocenediyl optionally substituted, including the carbon atoms to which each of the R 4  group are bonded; or 
         three distinct adjacent R 4  groups, taken together, form a naphthalene ring optionally substituted, including the carbon atoms to which each of the R 4  group are bonded; and 
       
       R 6  represents a hydrogen atom, a linear or branched C 1  to C 4  alkyl group or an phenyl group optionally substituted; or R 6 , when taken together with R 1 , forms a C 3 -C 9  C═N function-containing heterocycle optionally substituted and optionally containing one additional nitrogen or oxygen atom. 
     
   
   
       8 . The process according to  claim 1 , wherein L2 is a ligand of formula (2-F) or (2-G) 
     
       
         
         
             
             
         
       
       wherein the dotted lines in formula (2-G) indicate the presence of a phenyl or a naphthyl group; e represents 1 or 2; 
       R 1  and R 1′  represent, simultaneously or independently, a hydrogen atom, a linear, branched or cyclic C 1  to C 6  alkyl or alkenyl group optionally substituted; 
       R 2  and R 3 , represent, simultaneously or independently, a linear, branched or cyclic C 1  to C 6  alkyl group optionally substituted, a phenyl or naphthyl group optionally substituted; or the groups R 2  and R 3 , taken together, form a saturated or unsaturated ring optionally substituted, having 5, 6 or 7 atoms and including the phosphorus atom to which the R 2  and R 3  groups are bonded; 
       R 6  represents a hydrogen atom, a linear or branched C 1  to C 4  alkyl group optionally substituted, or a phenyl group optionally substituted; or R 6 , when taken together with R 1 , forms a C 3 -C 9  C═N function-containing heterocycle optionally substituted and optionally containing one additional nitrogen or oxygen atom. 
     
   
   
       9 . The process according to  claim 1 , wherein the base has a pK a  above 14. 
   
   
       10 . The process according to  claim 1 , wherein the base is an alkaline or alkaline-earth metal carbonates, an alkaline or alkaline-earth metal hydroxides, C 1-10  amidures, C 10-26  phosphazine or an alcoholate of formula (R 13 O) 2 M or R 13 OM′, wherein M is an alkaline-earth metal, M′ is an alkaline metal or an ammonium NR 14   4   + , R 13  stands for hydrogen or a C 1  to C 6  linear or branched alkyl radical and R 14  stands for a C 1  to C 10  linear or branched alkyl radical. 
   
   
       11 . The process according  claim 1 , wherein the substrate is a compound of formula (1) 
     
       
         
         
             
             
         
       
       wherein R a  and R b  represent, simultaneously or independently, a linear, branched or cyclic C 1 -C 30  aromatic, alkyl or alkenyl group optionally substituted; or 
       R a  and R b  are bonded together and form a C 4 -C 20  saturated or unsaturated group, optionally substituted; 
       and wherein the substituents of R a  and R b  are a COOR c , group, one, two or three halogen, OR c , NR c   2  or R c  groups, in which R c  is a hydrogen atom, a halogenated C 1 -C 2  group or a C 1  to C 10  cyclic, linear or branched alkyl, or alkenyl group.