Arabinogalactan propargyl ethers: Au-catalysed hydroamination by imidazols

Lyudmila A Grishchenko; Lidiya N Parshina; Lyudmila I Larina; Lyudmila A Belovezhets; Igor V Klimenkov; Alexander Yu Ustinov; Boris A Trofimov

doi:10.1016/j.carbpol.2020.116638

Arabinogalactan propargyl ethers: Au-catalysed hydroamination by imidazols

Carbohydr Polym. 2020 Oct 15:246:116638. doi: 10.1016/j.carbpol.2020.116638. Epub 2020 Jun 13.

Authors

Lyudmila A Grishchenko¹, Lidiya N Parshina¹, Lyudmila I Larina¹, Lyudmila A Belovezhets¹, Igor V Klimenkov², Alexander Yu Ustinov³, Boris A Trofimov⁴

Affiliations

¹ A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences, 1, Favorsky Str., 664033, Irkutsk, Russia.
² Limnological Institute, Siberian Branch, Russian Academy of Sciences, 3, Ulan-Batorskaya Str., 664033, Irkutsk, Russia.
³ Institute of Chemistry, Far East Branch, Russian Academy of Sciences, 159, Prosp. 100-letiya Vladivostoka, 690022, Vladivostok, Russia.
⁴ A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences, 1, Favorsky Str., 664033, Irkutsk, Russia. Electronic address: boris_trofimov@irioch.irk.ru.

PMID: 32747273
DOI: 10.1016/j.carbpol.2020.116638

Abstract

A method for the synthesis of pharmacologically prospective arabinogalactan (AG) imidazole- and benzimidazole derivatives in a yield of up to 97 % via Au(III)-catalyzed hydroamination of AG propargyl ethers has been developed. It is found that in the presence of 5 mol% HAuC1₄ and 10-fold excess imidazole relative to the propargyl groups, the hydroamination successfully competes with cross-linking processes to afford products soluble in DMSO and aqueous HC1 solutions (degree of substitution of imidazolylpropenyl fragments 0.5-1.8, yield 62-97 %). It is established that under the conditions of hydroamination Au(III) is reduced to give mainly Au(0) and minor amounts of Au(I), which are contained in AG imidazole derivatives as particles of 190-640 nm in size. Hydrochlorides of Au-containing AG imidazole derivatives show high bacteriostatic activity with respect to test gram-positive microorganisms and thus confirming their prospects as new AG-derived bioactive agents.

Keywords: Antimicrobial activity; Arabinogalactan functionalization; Gold-catalysis; Hydroamination; Imidazole derivatives; XPS study.