[8,15'-Biaspidospermidine]-3-carboxylicacid, 2,3-didehydro-6,7-epoxy-6',7',15-trihydroxy-16,17-dimethoxy-1'-methyl-,methyl ester, (5a,6b,7b,8a,12b,19a)-(2'b,5'a,6'b,7'a,12'b,19'a)-