Domino Reactions of Donor–Acceptor‐Substituted Cyclopropanes for the Synthesis of 3,3′‐Linked Oligopyrroles and Pyrrolo[3,2‐e]indoles

Abstract

Multiple displacement of oxygen: Electron-rich oligopyrroles and pyrrolo[3,2-e]indoles are generated by a domino process induced by donor-acceptor-substituted cyclopropanes. Up to seven molecules of water are eliminated, thus allowing the introduction of nitrogen and aromaticity.

Intramolecular donor–acceptor cyclopropane ring-opening cyclizations

“…Expanding upon their oligoacetal methodology, Werz and co-workers divulged a unique approach for the synthesis of 3,3 0 -linked bispyrroles and oligopyrroles (Scheme 4). 22 Treatment of diketones 13 with excess primary amines, carbamates or sulfonamides and 5 mol% p-TsOH or AcOH in benzene at reflux afforded 3,3 0 -linked bispyrroles 14 in 19-90% yield. The reaction proceeds via the bisimine 15 which undergoes cycloisomerization and water loss to give bispyrroles 14.…”

Ring Opening of Donor–Acceptor Cyclopropanes with N-Nucleo­philes

“…An original method for the synthesis of 3,3′-bipyrroles 126 from the Werz group 118,119 was based on the reaction between tricyclic compounds 125, the structure of which included fragments of two ketocyclopropanes as well as tetrahydrofuran, and primary amines (Scheme 64). 118 In some cases, diketopyrroles 127 were obtained as secondary prod- …”

New Dyes Based on Extended Fulvene Motifs: Synthesis through Redox Reactions of Naphthoquinones with Donor–Acceptor Cyclopropanes and Their Spectroelectrochemical Behavior

“…For both, the same tin(II) salt was employed, whicha llowedt he attachment of naphthoquinones 2 to aC 3 unit that wasp rovided by donor-acceptor cyclopropane 1 (Scheme 1). [6][7][8] In the presence of base and an oxidant, eithera tmospherico xygen or MnO 2 ,c ompounds of type 3 with afulvenem otif were generated.…”