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Mild Base‐Promoted Indole Annulation–Oxidative Cross‐ Coupling of 2‐Nitrocinnamaldehydes with β‐Tetralones for 3‐Naphthylindole and 3‐Naphthylbenzo[ g ]indole Fluorophores
Author(s) -
Poudel Tej Narayan,
Lee Yong Rok
Publication year - 2017
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201601327
Subject(s) - chemistry , annulation , indole test , aromatization , decarbonylation , intramolecular force , tetralones , oxidative coupling of methane , photochemistry , combinatorial chemistry , stereochemistry , organic chemistry , catalysis
This paper describes the transition metal‐free indole annulation–oxidative cross‐coupling of 2‐nitrocinnamaldehydes or ( E )‐3‐(1‐nitronaphthalen‐2‐yl)acrylaldehyde with β‐tetralones for the construction of diverse 3‐naphthylindole and 3‐naphthylbenzo[ g ]indole fluorophores in moderate to good yields. This unique annulation reaction proceeds via the domino Michael addition/hemiacetalization/intramolecular addition of an enolate to a nitro group/decarbonylation/oxidative aromatization sequence under transition metal‐free conditions without the use of an external reductant and oxidant. The synthetic utility of this protocol has been also demonstrated by evaluating the photophysical properties of the synthesized 3‐naphthylindole and 3‐naphthylbenzo[ g ]indole derivatives.