| 摘要 |
The invention relates to a process for the preparation of pyrido[2,1-a]isoquinoline derivatives of the formula wherein R2, R3 and R4 are as defined in the specification, comprising the steps of a) catalytic asymmetric hydrogenation of an enamine of the formula wherein R1 is lower alkyl, in the presence of a transition metal catalyst containing a chiral diphosphane ligand, b) introduction of an amino protecting group Prot and c) amidation of the ester to form an amide of formula wherein R2, R3, R4 and Prot are as defined in the specification.
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