(2R,8S)-4-benzyloxy-8-(tert-butyldimethylsilanyloxymethyl)-2-methyl-1-oxo-6-(5,6,7-trimethoxy-1H-indole-2-carbonyl)-1,2,3,6,7,8-hexahydro-3,6-diaza-as-indacene-2,3-dicarboxylic acid 3-benzyl ester 2-methyl ester