Gabriel-Coleman synthesis

In the first year of the 20th century, there was a new finding concerning the synthesis of pteridine, known as Gabriel-Coleman synthesis. In this method, pteridine derivatives are generally produced through the condensation of 2,3-diaminopyrimidine 55 with a-diketone (Eq. 5). One century has passed since the development of Gabriel-Coleman synthesis, however, modern synthetic procedures of tetrahydrobiopterin (43) conceptually depend on this synthe-... 

The application of Gabriel-Coleman synthesis to the synthesis of biopterin (30) is reliable, however, it has a serious problem in that the condensation of the pyrimidine precursor with asymmetrically substituted sugar derivatives is sometimes less regioselective or even nonregioselective. For example,... 

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