Patent ID: 8883805

Claim:
A compound of formula (II) or an enantiomer thereof, wherein R 1 is a phenylcarbonylmethyl, benzyl, naphthylmethyl, pyridinylmethyl, pyrimidinyl-methyl, quinolinylmethyl, isoquinolinylmethyl, quinazolinylmethyl, quinoxalinylmethyl, naphthyridinylmethyl or phenanthridinylmethyl group wherein the aromatic or heteroaromatic moiety is in each case mono- or disubstituted by R a , where the substituents may be the same or different and R a is a hydrogen, fluorine, chlorine or bromine atom or a cyano, methyl, trifluoromethyl, ethyl, phenyl, methoxy, difluoromethoxy, trifluoromethoxy or ethoxy group, or two R a radicals, when they are bonded to adjacent carbon atoms, may also be an —O—CH 2 —O— or —O—CH 2 —CH 2 —O— group, R 2 is a methyl, ethyl, propyl, isopropyl, cyclopropyl or phenyl group, and R 3 is a 2-buten-1-yl, 3-methyl-2-buten-1-yl, 2-butyn-1-yl, 2-fluorobenzyl, 2-chlorobenzyl, 2-bromobenzyl, 2-iodobenzyl, 2-methylbenzyl, 2-(trifluoromethyl)benzyl or 2-cyanobenzyl group.