A process for preparing a compound of the formula IA or IB:
wherein R is alkyl, aminoalkyl, halogenalkyl, aralkyl, cycloalkyl, cycloalkylalkyl, alkoxy, phenyl or substituted phenyl or pyridyl group; the term alkyl means carbon chain, straight or branched, containing from 1 to 18 carbon atoms; the term halogen represents fluorine, chlorine, bromine or iodine; the term cycloalkyl represents a saturated alicyclic group with 3 to 6 carbon atoms; the term aryl represents unsubstituted phenyl group or phenyl substituted by alkoxy, halogen or nitro group, the process comprising asymmetric hydrogenation of a compound of the formula II:
wherein R has the same meanings as above, using a chiral catalyst and a source of hydrogen.
一种制备式为IA或IB的化合物的方法:其中R是烷基,
氨基烷基,卤代烷基,芳基烷基,环烷基,环烷基烷基,烷氧基,苯基或取代苯基或
吡啶基;术语烷基表示碳链,直链或支链,含有1至18个碳原子;术语卤素代表
氟,
氯,
溴或
碘;术语环烷基表示具有3至6个碳原子的饱和脂环族基;术语芳基表示未取代的苯基或被烷氧基,卤素或硝基取代的苯基,该方法包括使用手性催化剂和氢源对式为II的化合物进行不对称氢化反应,其中R具有与上述相同的含义。