Patent ID: 7619101

Claim:
A process for the preparation of (S)-4-fluoromethyl-dihydro-furan-2-one of the formula comprising the step of converting a 4-fluoromethyl-5H-furan-2-one of the formula by way of a catalytic asymmetric hydrogenation in the presence of a chiral catalyst, wherein the chiral catalyst is a ruthenium or a rhodium complex catalyst containing a chiral diphosphine ligand selected from the group consisting of formula IV, V, VI, VII and VIII: wherein R 5 independently from each other is aryl, heteroaryl, cylcoalkyl or lower alkyl; R 6 is lower alkyl; R 7 is lower alkyl; R 8 is lower alkyl, lower alkoxy, hydroxy or —O—C(O)-lower alkyl; R 9 and R 10 independently from each other are hydrogen, lower alkyl, lower alkoxy or lower dialkylamino; or R 8 and R 9 which are attached to the same phenyl group, or R 9 and R 10 which are attached to the same phenyl group, or both R 8 , taken together, are —X—(CH 2 ) n —Y—, wherein X is —O— or —C(O)O—, Y is —O— or N(lower alkyl)- and n is an integer from 1 to 6; or R 8 and R 9 , or R 9 and R 10 , together with the carbon atoms to which they are attached, form a naphthyl, tetrahydronaphthyl or dibenzofuran ring; R 11 independently from each other is selected from the group consisting of unsubstituted phenyl, phenyl substituted by 1 to 5 substituents independently selected from the group consisting of lower alkyl, lower alkoxy, lower dialkylamino, morpholino, phenyl and lower trialkylsilyl, unsubstituted naphthyl, and napthyl substituted by 1 to 7 substituents independently selected from the group consisting of lower alkyl, lower alkoxy, lower dialkylamino, morpholino, phenyl and lower trialkylsilyl; and R 12 independently from each other is lower alkyl.