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Regioselective Synthesis of Imidazo[1,5‐ b ]pyridazines by Cascade Cyclizations of 1,2‐Diamino‐4H‐phenylimidazole with 1,3‐Diketones, Acetoacetic Ester and Their Derivatives
Author(s) -
Kruzhilin Alexey A.,
Kosheleva Evgeniya A.,
Shikhaliev Khidmet S.,
Denisov Gleb L.,
Vandyshev Dmitriy Yu.
Publication year - 2021
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.202101372
Subject(s) - chemistry , triethyl orthoformate , regioselectivity , yield (engineering) , two dimensional nuclear magnetic resonance spectroscopy , acetone , dimethylformamide , nuclear magnetic resonance spectroscopy , proton nmr , medicinal chemistry , stereochemistry , organic chemistry , solvent , catalysis , materials science , metallurgy
In this study we investigated the cascade heterocyclisation reactions of 1,2‐diamino‐4H‐phenylimidazole with dimethylaminomethylidene (ethoxymethylidene) by the derivatives of acetoacetic ester, acetyl acetone, and aryl(hetaryl)butane‐1,3‐diones. As a result of the studied processes 7‐amino‐2‐R‐3‐R1‐5‐phenylimidazo[1,5‐ b ]pyridazines were obtained, whose structures were proved by means of 1 H NMR, 13 C NMR, XRS, and NOESY spectroscopy. Heterocyclisation conditions were optimised to obtain target products with high yields. A probable mechanism for regioselective processes was suggested. It was found that three‐component processes with initial diamine, 1,3‐dicarbonyl compounds and triethyl orthoformate or dimethylformamide dimethylacetal result in similar products. The yield of these reactions was slightly reduced in comparison to the two‐component processes.