Pentanamide,N,N'-[(1S,2S)-2-[(1S,2R,3S)-3-[[(1,1-dimethylethyl)dimethylsilyl]oxy]-2-methylcyclopentyl]-1-[(8S)-8-methyl-1,4-dioxaspiro[4.5]dec-6-en-8-yl]-1,3-propanediyl]bis[4,5-bis[[[(1-ethoxyethyl)thio]acetyl]amino]-