PROCESS FOR THE PREPARATION OF 8-(4-AMINOPHENOXY)-4H PYRIDO2,3-B PYRAZIN-3-ONE DERIVATIVES

The present invention pertains generally to the field of organic chemical synthesis, and in particular to certain methods for the synthesis of 8-(4-aminophenyoxy)-4H pyrido2.3-bipyrazin-3-one and related compounds (de noted herein as (3)) from 4-(4-aminophenyoxy)pyridine-2, 3-diamine and related compounds (denoted herein as (1)), by reaction with glyoxylic acid (denoted herein as (2)). The compounds (3) are useful in the synthesis of known anti cancer agents, such as 1-(5-tert-butyl-2-(4-methyl-phenyl)- pyrazol-3-yl)-3-2-fluoro-4-(3-oxo-4H-pyrido 2,3-b pyrazin-8-yl)oxyphenylurea.