The polyketide chain in rubrofusarin biosynthesis has been shown to adopt the folding pattern B by the incorporation of 13CH313CO2Na and of CD313CO2Na, with observation of the b-isotopic shifts in the 13C n.m.r. spectrum, in the rubrofusarin derivative (5). The extent of retention of deuterium at the various sites is interpreted in terms of an unusual sequence of biosynthetic steps. The assignment of the 13C n.m.r. spectrum of rubrofusarin dimethyl ether (2) was made with the aid of specific deuteriation and 1H-13C n.O.e.'s as well as more standard techniques.
Department of Chemistry
University of Cambridge