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Synthesis of naphthothiophene derivatives through polar Diels-Alder reactions employing 5-nitrobenzothiophene as electrophile. Microwave irradiation vs classical thermal conditions
1  Universidad Nacional del Litoral. Santa Fe. Argentina


Herein we report a simple, economical and efficient one-step procedure to synthesize the naphtho[2,1-b]thiophene ring system in good to excellent yield through the polar Diels-Alder reactions of 5-nitro-3-acetylbenzothiophene and dienes of different nucleophilicity. In thermal conditions the reactions were developed in molecular solvents; moreover the reaction system was exposed to microwave irradiation as a complement of reaction conditions.

Keywords: Nitrobenzothiophene, electrophile, Diels-Alder
Comments on this paper
Murali Venkata Basavanag Unnamatla
elimination of nitro group in the reaction
hello madam

congratulation to your work but i have small question, while observing the reaction i have seen that there was elimination of Nitro group during the reaction, can you please explain how it is possible .
Claudia Della Rosa
Hello, It has been demonstrated that in contrast to the acylated aromatic heterocycles, nitro aromatic heterocycles, such as nitrofurans, nitropyrroles, nitrothiophenes, nitro selenophenes, nitrobenzofurans, nitroindoles and nitrobenzothiophenes react efficiently with the different dienes in polar Diels-Alder reactions, with the nitro group inducing side selectivity. This substituent is easily extrused under thermal conditions.

All addition products showed extrusion of the nitro group as nitrous acid.


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