Studies in relation to biosynthesis. Part 47. Phomazarin. Part 1. The structure of phomazarin, an aza-anthraquinone produced by Pyrenochaeta terrestris Hansen

Abstract

The structure (4) has been established for phomazarin, 6-n-butyl-2-carboxy-3,4,8-trihydroxy-7-methoxy-1-aza-anthraquinone, from n.m.r. and i.r. spectra, and degradative studies of phomazarin and its derivatives. Nitrogen-15 chemical shifts, and ¹⁵N–¹H and ¹³N–¹⁵C coupling constants in derivatives of biosynthetically ¹⁵N-enriched phomazarin are of particular utility in differentiating between possible alternate structures.