Five-membered 2,3-dioxoheterocycles: XC. Reaction of 4,5-bis(methoxycarbonyl)-1H-pyrrole-2,3-diones with enaminoesters. crystal and molecular structure of 4-methyl 9-ethyl 7-benzyl-3-hydroxy-8-methyl-1-(4-methoxyphenyl)-2,6-dioxo-1,7-diazaspiro[4.4]nona-3,8-diene-4,9-dicarboxylate

1-Aryl-4,5-bis(methoxycarbonyl)-1H-pyrrole-2,3-diones react with ethyl 3-(benzylamino)but-2-enoate and ethyl 3-(benzylamino)-3-phenylacrylate giving 4-methyl 9-ethyl 1-aryl-7-benzyl-3-hydroxy-8-methyl- and 4-methyl 9-ethyl 1-aryl-7-benzyl-3-hydroxy-8-phenyl-2,6-dioxo-1,7-diazaspiro[4.4]nona-3,8-diene-4,9-dicarboxylates.