Antibiotic WR-141

(3aS,15R)-3,3aβ,5,8,11,13bβ-Hexahydro-7,8,12,15-tetrahydroxy-5β,9β-dimethyl-8α,11α-ethanofuro[2,3-e]naphtho[2,3-c:6,7-c']dipyran-2,6,13(9H)-trione