Alkylation of 1,3-Dicarbonyl Compounds and Their Analogues with 2-Halomethyl(ethoxycarbonyl)(diethoxyphosphorylmethyl)fu
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lation of 1,3-Dicarbonyl Compounds and Their Analogues with 2-Halomethyl(ethoxycarbonyl)(diethoxyphosphorylmethyl)furans L. M. Pevznera,* and A. I. Ponyaeva a St.
Petersburg State Institute of Technology (Technical University), St. Petersburg, 190013 Russia *e-mail: [email protected] Received February 27, 2020; revised February 27, 2020; accepted March 5, 2020
Abstract—2-Halomethyl derivatives of phosphonocarboxylic acid esters of the furan series react with acetylacetone, acetoacetic, malonic and cyanoacetic ether in the absolute ethanol–dioxane (1 : 10) medium in the presence of sodium ethylate with the formation of monoalkyl derivatives. Reactions of 3-(furylmethyl)acetylacetone and 2-(furylmethyl)acetoacetate with hydrazine hydrate lead to the formation of phosphorus-containing (furyl)(pyrazolyl)methanes and (furyl)(pyrazolonyl)methanes, respectively. The latter in solutions exist exclusively in hydroxy-form. Keywords: 1,3-dicarbonyl compounds, 2-halogenomethylfurans, pyrazoles, pyrazolones, keto-enol tautomerism
DOI: 10.1134/S1070363220080125 1,3-Dicarbonyl compounds and their analogues are widely used in the synthesis of the most diverse heterocyclic compounds. Introduction of additional heterocyclic fragment in their structure allows the use such substances for obtaining of hybrid systems, containing heterocyclic residues of various nature bound with a linker what is widely used to create inhibitors of various enzymes [1]. In this connection bicyclic compounds containing the furan fragment and the electron-accepting heterocyclic residue linked by methylene group are of great interest. The most obvious pathway to such structures includes alkylation of 1,3-dicarbonyl compounds and their analogues with halomethylfurans and subsequent heterocyclization. To our surprise, no example of alkylation of 1,3-dicarbonyl compounds with halomethylfurans was reported about. Therefore, the purpose of this work was a study of the possibility of using recently synthesized by us
[2, 3] 2-halomethyl derivatives of phosphonocarboxylates of the furan series in this reaction. It was proposed also to use the alkylation products for preparing of (furylmethyl)pyrazoles because the pyrazole ring is easily formed under mild conditions while interaction of derivatives of acetylacetone or acetoacetic ester with hydrazine hydrate. The first step of our work was to establish the sequence of stages of obtaining the derivatives of 1,3-dicarbonyl compounds, containing functionally substituted furan fragment. Possible options were alkylation of 1,3-dicarbonyl compound with 2-halogenmethylfuran followed by bromination of methyl group of the furan moiety with N-bromosuccinimide and its subsequent functionalization by means of the nucleophilic substitution reactions, or use of the ready-made functionalized 2-halomethylfurans. Ethyl 2-chloromethyl-5-methylfuran-3-carboxylate 1 was used as a model compound. The reaction with acetylacetone was carried out in a mixture of absolute
Scheme 1.
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PEVZNER, PONYAEV
ethanol and dioxane (1 :
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