Et. Pelkey et al., AN ABNORMAL BARTON-ZARD REACTION LEADING TO THE PYRROLO[2,3-B]INDOLE RING-SYSTEM, Chemical communications, (16), 1996, pp. 1909-1910
The reaction of 3-nitro-N-(phenylsulfonyl)indole 1 with ethyl isocyano
acetate 2 under the Barton-Zard pyrrole synthesis conditions gives eth
yl nyl)-1,8-dihydropyrrolo[2,3-b]indole-2-carboxylate 3 rather than th
e anticipated ethyl nyl)-2,4-dihydropyrrolo[3,4-b]indole-3-carboxylate
4.