Nitrobutadienes as powerful benzannulating agents: An unprecedented easy access to rare nitroindoles

We report herein an original protocol to the indole nucleus, which could contribute to significantly expand the synthetic access to a heterocyclic moiety of undeniable paramount importance. The protocol consists in the construction of the benzene ring onto a pyrrole (benzannulation) starting from 2,...

Full description

Saved in:
Bibliographic Details
Published in:Tetrahedron 2019-08, Vol.75 (33), p.4506-4515
Main Authors: Pagano, Angela, Mancinelli, Michele, Bianchi, Lara, Giorgi, Gianluca, Maccagno, Massimo, Petrillo, Giovanni, Tavani, Cinzia
Format: Article
Language:English
Subjects:
2,3-Dinitrobutadienes
Benzannulation
Michael addition
Nitroindoles - dinitroindoles
Stereoselectivity
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We report herein an original protocol to the indole nucleus, which could contribute to significantly expand the synthetic access to a heterocyclic moiety of undeniable paramount importance. The protocol consists in the construction of the benzene ring onto a pyrrole (benzannulation) starting from 2,3-dinitro-1,3-butadienes. This appealing, metal-free process characterized by high atom economy and mild reaction conditions allows to synthesize indoles possessing nitro group(s) on the benzene ring: a result which cannot be likewise easily obtained by exploiting most common pathways such as functionalization of a preformed indole or heteroannulation of a suitable benzene derivative. From a mechanistic point of view, a stepwise, ionic process is suggested by the identification of a pivot dihydroindole intermediate whose interception facilitates some selectivity in the preparation of different nitroindoles. [Display omitted]
ISSN:0040-4020
1464-5416
DOI:10.1016/j.tet.2019.06.038