dipotassium 4-carboxy-7-hydroxy-11b-methyl-8-methylidenetetradecahydro-6a,9-methanocyclohepta[a]naphthalen-2-yl 6-O-{4-[(4-azido-2-nitrophenyl)amino]butanoyl}-2-O-(3-methylbutanoyl)-3,4-di-O-sulfonatohexopyranoside