17aH-8a,16-endo-Oxiranonaphtho[2',3':5,6]cyclohepta[1,2-c]xanthene-17a-carboxylicacid,7-chloro-1,2,3,5,8,9,15,16-octahydro-1,4,6,10,13,14-hexahydroxy-18-(hydroxymethyl)-5,9,15-trioxo-,methyl ester, [1S-(1a,8aa,16a,17aa,18R*,20R*)]-