Studies on fungal products. Part 13. Isolation and structures of dithiosilvatin and silvathione, novel dioxopiperazine derivatives from Aspergillus silvaticus
Dithiosilvatin (1), an epidithiodioxopiperazine, and silvathione (2), a dioxopiperazinethione, were isolated from Aspergillus silvaticus. Their structures were established on the basis of chemical reactions and spectroscopic evidence. Dithiosilvatin (1) is a very rare example of naturally occurring epidithiodioxopiperazines, a class of compounds which appear to be biosynthesized originally from glycine, and phenylalanine or tyrosine. Silvathione (2) is the second example of a natural dioxopiperazinethione and is biogenetically a possible key intermediate in the formation of trioxopiperazine from epidithiodioxopiperazine.