Abstract Our approach to achieve a partial synthesis of methanopterin (1) started from 6- acetyl-O 4-isopropyl-7-methylpterin (20) which was obtained either by condensation from 6- isopropoxypyrimidine-2, 4, 5-triamine (19) and pentane-2, 3, 4-trione (6) or from 6- isopropoxy-5-nitrosopyrimidine-2, 4-diamine (21) and pentane-2, 4-dione (= acetylacetone; 22)(Scheme 2). NaBH 4 reduction of 20 led to 6-(1-hydroxyethyl)-O 4-isopropyl-7- ...
