Synlett 2020; 31(07): 691-694
DOI: 10.1055/s-0039-1691600
letter
© Georg Thieme Verlag Stuttgart · New York

Advanced Catalyst-Free Pseudo-Six-Component Synthesis of Tetrahydrodipyrazolopyridines in Water by Using Ammonium Carbonate as an Ecofriendly Source of Nitrogen

Fatemeh Tamaddon
Department of Chemistry, Faculty of Science, Yazd University, Yazd 89195-741, Iran   eMail: ftamaddon@yazd.ac.ir   eMail: khorramali58@gmail.com
,
Ali Khorram
› Institutsangaben
We gratefully thank the Yazd University Research Council for financial support.
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Publikationsverlauf

Received: 16. Oktober 2019

Accepted after revision: 04. Januar 2020

Publikationsdatum:
04. Februar 2020 (online)


Abstract

This work describes an improved environmentally friendly method for the synthesis of tetrahydrodipyrazolopyridines (THDPPs) in water through a catalyst-free pseudo-six-component reaction of alkyl acetoacetates, hydrazine hydrate, and ammonium carbonate with an aldehyde in a mole ratio of 2:2:1:1 at room temperature. The ammonium carbonate serves as a green source of nitrogen for the central 1,4-dihydropyridine ring in the THDPPs. Methyl acetoacetate reacts faster than either ethyl or propyl acetoacetate in this method. The product precipitates during the reaction and is simply collected by filtration. Advantages of this environmentally benign method include no use of an organic solvent, no hazardous waste, rapid clean reactions, and excellent yields of products.