Previous papers from this laboratory have described an unambiguous approach to the synthesis of 6-substituted pteridines by guanidine cyclization of 2-amino-3-cyano (or alkoxycarbonyl) pyrazines suitably substituted at position 5. These latter critical intermediates were prepared in turn by cyclization of aminomalononitrile (or esters of a- aminocyanoacetic acid) with an a-ketoaldoxime, followed by deoxygenation of the ...
