1,4-dioxa-7-azaspiro[4.4]-nonane-8(S)-carboxylic acid methyl ester

methyl 1-[2-[[2-[[2-amino-9-[[3-hydroxy-1-[[1-(2-methoxycarbonyl-4-oxopyrrolidin-1-yl)-3-methyl-1-oxobutan-2-yl]amino]-1-oxobutan-2-yl]carbamoyl]-4,6-dimethyl-3-oxophenoxazine-1-carbonyl]amino]-3-hydroxybutanoyl]amino]-3-methylbutanoyl]-3-oxopyrrolidine-2