Aryltellurium Trihalides in the Synthesis of Heterocyclic Compounds (Microreview)

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Aryltellurium trihalides in the synthesis of heterocyclic compounds (microreview) Mykola M. Kut*1, Mikhaylo Yu. Onysko1 1

Uzhhorod National University, 46 Pidgirna St., Uzhhorod 88000, Ukraine; е-mail: [email protected]

Published in Khimiya Geterotsiklicheskikh Soedinenii, 2020, 56(5), 503–505

Submitted March 11, 2020 Accepted April 10, 2020

The review is devoted to the methods of synthesis of furan, pyran, and thiazole derivatives employing aryltellurium trihalides published in 1983–2019. Introduction Aryltellurium trihalides are used as electrophilic reagents in the synthesis of organotellurium compounds1,2 with high biological activity.3–10 This microreview focuses on the use of synthetically available p-alkoxyphenyltellurium triha-

lides11 in the reactions of electrophilic intramolecular cyclization in the synthesis of mono- and polycyclic furan, pyran, and thiazole derivatives.

Synthesis of furan derivatives The reactions of aryltellurium trihalides with γ,δ-alkenyl alcohols, carbonyl compounds, acids, and their derivatives are the most studied. The reaction of p-alkoxy(alkyl)phenyltellurium trichlorides 1a,c,d with γ,δ-unsaturated alcohols and ethers 2 in CHCl3 allows the one-step synthesis of tetrahydrofuran derivatives 3 with an exocyclic aryltelluriium fragment in 65–98% yields. The use of p-methoxyphenyltellurium tribromide (1b) in the synthesis of tellurium-functionalized furan reduces the yields of products 3.12 Cyclization of sterically hindered alkenols with aryltellurium trichlorides results in 2,3,5-substituted tetrahydrofurans in high yields (85–98%).13 The use of γ,δ-alkenols containing a double carbon–carbon bond in the alicycles in reactions with aryltellurium trihalides results in the annulation of the furan ring and the formation of bicyclic furans.12 The use of alkenyl derivatives of glycols or dibenzyl esters allows the preparation of 2,5-substituted tetrahydrofurans suitable for further functionalization. The yields of cyclization products of glycols reach 96%; the use of benzyl esters reduces the yields of the target products to 65%.13

Benzotetrahydrofurans 5 are formed in high yields in the reaction of p-methoxyphenyltellurium trichloride (1a) with 2-allylcyclohexanol or o-allylphenols 4 in CHCl3.

Mykola M. Kut, Assistant, Department of Organic Chemistry, Uzhhorod National University, Ukraine. He defended his PhD thesis in 2019 at the Institute of Organic Chemistry of the National Academy of Sciences of Ukraine. His scientific interests include the development of new methods for the synthesis of nitrogen-containing heterocyclic compounds by electrophilic cyclization, the chemistry of organic derivatives of selenium and tellurium, and the directed synthesis of biologically active compounds.

Mikhaylo Yu. Onysko, Associate Professor, Department of Organic Chemistry, Uzhhorod National University, Ukraine. He defended his PhD thesis in 2001 at the Institute of Organic Chemistry of the National Academy of Sciences of Ukraine. His scientific interests include the development of new method

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