Specific inhibitors in vitamin biosynthesis. Part II. Syntheses of pterinswith extended side chains at C-6

In order to provide access to highly functionalised pterins as potential in hibitors of enzymes in the folate biosynthesis pathway, the Wittig reaction has been applied to 6-formylpterin (1b) and 6-formyl-7,7-dihydro-7,7-dimet hylpterin (6). Dimethylaminomethylene and pivaloyl moieties were found to b e suitable protecting groups for the 2-amino group of the pterins compatibl e with reactions of phosphoranes with a variety of substituents including e sters, ethers and amides. In contrast, attempts to prepare extended side ch ains at C-6 using aldol and Claisen chemistry were unsuccessful.