Experimental and DFT mechanistic insights into one-pot synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones under catalysis of DBU-based ionic liquids
In: New Journal of Chemistry, Jg. 44 (2020), S. 16594-16601
Online
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Zugriff:
Benzylation of DBU followed by anion exchange of the resulting salt with trifluoroacetate gave nearly quantitatively the ionic liquid [Bn-DBU][TFA]. It is shown here to be an efficient catalyst for the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones via the three-component reaction of phthalhydrazide, aromatic aldehydes, and active α-methylene nitriles. DFT calculations at the B3LYP/SVP level and the experimental results are in agreement with a three-step mechanism for this reaction. Based on the DFT calculations, the catalytic effect largely arises from the intrinsic ionic properties of the ionic liquid rather than its action as a simple base. These calculations also predict the existence of two close-in-energy activated complexes whose rate determining roles and energies depend on their interaction with the anionic component of the ionic liquid, as [Bn-DBU][TFA] has shown a higher catalytic activity than [Bn-DBU][OAc]. This mechanistic approach opens up new and promising insights into the rational design of ionic liquid catalysts for the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones. The synthetic method presented here has several prominent advantages.
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Experimental and DFT mechanistic insights into one-pot synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones under catalysis of DBU-based ionic liquids
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Autor/in / Beteiligte Person: | Mehrdad, Morteza ; Roohi, Hossein ; Rad-Moghadam, Kurosh ; Sara Fallah Ghasemi Gildeh ; Ghauri, Khatereh ; Sahar Fallah-Ghasemi Gildeh |
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Zeitschrift: | New Journal of Chemistry, Jg. 44 (2020), S. 16594-16601 |
Veröffentlichung: | Royal Society of Chemistry (RSC), 2020 |
Medientyp: | unknown |
ISSN: | 1369-9261 (print) ; 1144-0546 (print) |
DOI: | 10.1039/d0nj03478a |
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