Selective reduction of esters to alcohols

A process of production of a compound of formula (II):

• wherein
• R1 is an aromatic ring system which is unsubstituted or an aromatic ring system which is substituted;
• a heteroaromatic ring system which is unsubstituted or a heteroaromatic ring system which is substituted;
• an aliphatic ring system which is unsubstituted or an aliphatic ring system which is substituted;
• —CH3;
• —CH2CH3;
• an unsubstituted C3-C22 alkyl group, which can be linear or branched and which can also be partially unsaturated;
• or a substituted C2-C22 alkyl group, which can be linear or branched and which can also be partially unsaturated, wherein
• the process comprises conducting a selective reduction of a compound of formula (I):
• wherein
• R is a linear C1-C6-alkyl group, which can be substituted;
• a branched C3-C6-alkyl group, which can be substituted or a benzyl group, which can be substituted, and
• R1 is an aromatic ring system which is unsubstituted or an aromatic ring system which is substituted;
• a heteroaromatic ring system which is unsubstituted or a heteroaromatic ring system which is substituted;
• an aliphatic ring system which is unsubstituted or an aliphatic ring system which is substituted;
• —CH3;
• —CH2CH3;
• an unsubstituted C3-C22 alkyl group, which can be linear or branched and which can also be partially unsaturated;
• or a substituted C2-C22 alkyl group, which can be linear or branched and which can also be partially unsaturated, or
• R and R1 form together a 4 to 7 membered ring system, which can be substituted, and wherein
• the selective reduction is carried out in the presence of at least one transition metal catalyst of formula (III):
• [M(L)(X)a(L′)b] (III), wherein
• M is a transition metal and
• X is an anion, and
• L′ is a monodentate ligand, and
• L is a tridentate ligand of formula (IV):
• wherein
• R3 is a linear C1-C4 alkyl group, which can be substituted;
• a branched C3-C4 alkyl group, which can be substituted;
• or a phenyl group, which can be substituted,
• R4 is H;
• a linear C1-C4 alkyl group, which can be substituted;
• a branched C3-C4 alkyl group, which can be substituted;
• or OC1-C2alkyl,
• R5 is H;
• a linear C1-C4 alkyl group, which can be substituted;
• a branched C3-C4 alkyl group, which can be substituted;
• or OC1-C2alkyl, or
• R4 and R5 form a C4-C8 ring system, which can be aliphatic or aromatic, and
• R6 is H;
• a linear C1-C4 alkyl group, which can be substituted;
• a branched C3-C4 alkyl group, which can be substituted;
• or OC1-C2alkyl,
• R7 is H;
• a linear C1-C4 alkyl group, which can be substituted;
• a branched C3-C4 alkyl group, which can be substituted;
• or OC1-C2alkyl,
• R8 is H or a linear C1-C4 alkyl group, which can be substituted;
• a branched C3-C4 alkyl group, which can be substituted,
• R9 is —CH3 or —CH2CH3,
• m is 0, 1 or 2, and
• n is 0, 1 or 2,
• with the proviso that the sum of m+n is 1 or 2,
• o is 2 or 3,
• a is 0, 1, 2, or 3, and
• b is 0, 1, 2, or 3,
• with the proviso that the sum of a+b is 2, 3 or 4.