4,​7,​10,​13-​Tetraoxa-​16-​azaheptadecanoic acid, 16-​[2-​[2-​[2-​(2-​azidoethoxy)​ethoxy]​ethoxy]​ethyl]​-​17-​[(3',​6'-​dihydroxy-​3-​oxospiro[isobenzofur​an-​1(3H)​,​9'-​[9H]​xanthen]​-​5-​yl)​amino]​-​17-​thioxo-