(2aS,4S,8bR)-1-Benzyl-5-hydroxy-6,8-dimethoxy-7-methyl-2-oxo-1,2,2a,3,4,8b-hexahydro-1,3-diaza-cyclobuta[a]naphthalene-4-carboxylic acid methyl ester

(2aS,4R,8bR)-1-Benzyl-5-hydroxy-6,8-dimethoxy-7-methyl-2-oxo-2,2a,4,8b-tetrahydro-1H-1,3-diaza-cyclobuta[a]naphthalene-3,4-dicarboxylic acid 3-tert-butyl ester 4-methyl ester

(2aS,4R,8bR)-1-Benzyl-5-benzyloxy-4-benzyloxymethyl-6,8-dimethoxy-7-methyl-2-oxo-2,2a,4,8b-tetrahydro-1H-1,3-diaza-cyclobuta[a]naphthalene-3-carboxylic acid tert-butyl ester