9H-fluoren-9-ylmethyl N-[(2S)-1-[[(2S)-1-[[(E)-3-[(6aS)-3-[3-[[(6aS)-2-methoxy-6,11-dioxo-8-[(E)-prop-1-enyl]-5-(2-trimethylsilylethoxymethyl)-6a,7-dihydropyrrolo[2,1-c][1,4]benzodiazepin-3-yl]oxy]propoxy]-2-methoxy-6,11-dioxo-5-(2-trimethylsilylethoxymethyl)-6a,7-dihydropyrrolo[2,1-c][1,4]benzodiazepin-8-yl]prop-2-enyl]amino]-1-oxopropan-2-yl]amino]-3-methyl-1-oxobutan-2-yl]carbamate