Process for the preparation of pyrido[2,1-a] isoquinoline derivatives

This application claims the benefit of European Patent Application No. 07150174.6, filed Dec. 19, 2007, which is hereby incorporated by reference in its entirety.

A major task in the synthesis of the compounds of formula I is the introduction of the chiral centers in the pyrido[2,1-a]isoquinoline moiety, which in the synthesis according to the PCT Int. Appl. WO 2005/000848 involves late stage enantiomer separation by chiral HPLC. Such a process is however difficult to manage on technical scale. The problem to be solved was therefore to find a suitable process alternative which allows obtaining the desired optical isomer in an earlier stage of the process, affords a higher yield and which can be conducted on technical scale.

All documents cited to or relied upon herein is expressly incorporated herein by reference.

The present invention relates to a process of the preparation of pyrido[2,1-a]isoquinoline derivatives of the formula

wherein R², R³ and R⁴ are each independently selected from the group consisting of hydrogen, halogen, hydroxy, lower alkyl, lower alkoxy and lower alkenyl, wherein lower alkyl, lower alkoxy and lower alkenyl may optionally be substituted by a group consisting of lower alkoxycarbonyl, aryl and heterocyclyl, and the pharmaceutically acceptable salts thereof, which are useful for the treatment and/or prophylaxis of diseases which are associated with DPP IV.

The present invention relates particularly to a process of the preparation of a pyrido[2,1-a]isoquinoline derivative of the formula

Pyrido[2,1-a]isoquinoline derivatives of the formula I are disclosed in PCT International Patent Appl. WO 2005/000848.

Provided is a process for the preparation of pyrido[2,1-a]isoquinoline derivatives of the formula

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Industry Class:
Organic compounds -- part of the class 532-570 series

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