New method of pyrrole acylation by microwave irradiation
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MARIN, Ion. New method of pyrrole acylation by microwave irradiation. In: International Conference of Young Researchers . Ediția 9, 11 noiembrie 2011, Chişinău. Chişinău: Tipogr. Simbol-NP SRL, 2011, p. 62. ISBN 978-9975-4224-7-5.
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International Conference of Young Researchers
Ediția 9, 2011
Conferința "International Conference of Young Researchers "
Chişinău, Moldova, 11 noiembrie 2011

New method of pyrrole acylation by microwave irradiation


Pag. 62-62

Marin Ion
 
Institute of Chemistry
 
Disponibil în IBN: 19 mai 2021


Rezumat

During the last decades microwave (MW) irradiation has became an increasingly valuable tool in organic chemistry, since it offers a versatile and facile pathway in a large variety of syntheses. Thus, a large number of organic reactions can be carried out under MW irradiation in higher yields, shorter reaction time and milder conditions. The emphasis of this work was to develop a new method for pyrrole diacylation using microwave irradiation. It is well known from the literature that 2,5-diacetylpyrrole can be used as starting material for obtaining polyquinolin by Friedlander condensation. The direct acylation of pyrrole with acetic anhydride occur in harsh conditions (6 h, high-pressure bomb heated to 300-320°C), leading mainly to 2-acetylpyrrole (39%) and a small amount of 3acetylpyrrole (8%)[1]. Subsequent acylation of 2-acetylpyrrole (glacial acetic acid and trifluoroacetic anhydride under N2 over 14 days) occur also to 2 isomers: 2,5-diacetylpyrrole (16%) and 2,4-diacetylpyrrole (45%)[2].formulaWe have developed a new method of diacylation of pyrrole using microwave irradiation.The advantages of this method consist in shorter reaction time and milder reactions conditions, the yields being basically the same. First reaction occurs in 15 minutes with 2-acetylpyrrole formation (25%) and don’t have impurities. The second reaction was observed that is finished in 50 min, but also mix of two isomers, which was chromatographed and obtained 2,5diacetylpyrrole (10% ) like target compound. Its structure was demonstrated by 1H-RMN, 13C-RMN and COSY-45. In conclusion, we have developed new and straightforward methods for obtaining of diacetylpyrrole which allows to save time and reagents.

Cuvinte-cheie
microwave, pyrrole, 2-acetylpyrrole, 2, 5-diacetylpyrrole