Syntheses and Reactions of Chloro-2-isopropyl-5-isobutylpyrazines Syntheses of Deoxymutaaspergillic Acid and 2-Hydroxy-3-isobutyl-6-isopropylpyrazine 1-Oxide

DL-Valyl-lencyl anhydride (III) was converted to mono- and di-chloro-isopropyl-isobutylpyrazines by treatment with phosphoryl chloride. These mono-chloropyrazines (VII and VIII) were oxidized and the products were converted to 2-isobutyl-5-isopropylpyrazine 1- and 4-oxides (XIV and XV) via hydrazino compounds. On the other hand, starting from 2-chloro-3-isobutyl-6-isopropylpyrazine (VII), two fungal metabolites, deoxymutaaspergillic acid (I) and 2-hydroxy-3-isobutyl-6-isopropylpyrazine 1-oxide (II), were prepared.