The reaction of 3-nitro-N-(phenylsulfonyl)indole 1 with ethyl isocyanoacetate 2 under Barton-Zard pyrrole synthesis conditions (1) gave a compound 3 that appeared to be the desired ethyl 4-(phenylsulfonyl)-2,4-dihydropyrrolo[3,4-b]indole-3-carboxylate 4 by all criteria (IR, NMR, UV, MS, and elemental analysis) (Scheme 1).

1. Barton, D.H.R.; Zard, S.Z. J. Chem. Soc., Chem. Commun., 1985, 1098.; Barton, D.H.R.; Kervagoret, J.; Zard, S.Z. Tetrahedron, 1990, 46, 7587.

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