-3-{(E)-2-[(1R,3R,4S)-4-Chloro-3 -methoxycyclohexyl]-1-methylvinyl} -8-ethyl-5,6,8,11,12,13,14,15,16,17,18 ,19,24,25,26,26a-hexaecahydro -5,19-dihydroxy-14,16-dimethoxy -4,10,12,18-tetramethyl-15,19-epoxy -3H-pyrido[2,1-c][1,4]oxaazacyclotricosine -1,7,20,21(4H,23H)-tetrone