New bisphosphonium salt containing a 1,4-dihydroxynaphthalene moiety: molecular and supramolecular structure
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Russian Chemical Bulletin, International Edition, Vol. 69, No. 11, pp. 2140—2146, November, 2020
New bisphosphonium salt containing a 1,4-dihydroxynaphthalene moiety: molecular and supramolecular structure N. R. Khasiyatullina, A. T. Gubaidullin, A. M. Shinkareva, D. R. Islamov, and V. F. Mironov A. E. Arbuzov Institute of Organic and Physical Chemistry,* Kazan Scientific Center of the Russian Academy of Sciences, 8 ul. Akad. Arbuzova, 420088 Kazan, Russian Federation. E-mail: [email protected] Bisphosphonium salt containing a 1,4-dihydroxynaphthyl-substituted moiety was synthesized in high yield by the reaction of 2-methyl-1,4-naphthoquinone with three equivalents of triphenylphosphine and hydrogen bromide. The structure of the synthesized bisphosphonium salt was determined by NMR spectroscopy and X-ray diffraction. Key words: triphenylphosphine, 2-methyl-1,4-naphthoquinone, diylide, bisphosphonium salt, molecular and supramolecular structure.
The chemistry of quinones and related compounds has been extensively developed due to the wide occurrence of these compounds in nature and their diverse biological activities, in particular, the antitumor effect.1—5 In recent years, a triarylphosphonium group is commonly used to increase the efficacy of antitumor activity. This group is introduced into anticancer or contrast agents and enables the targeting of cancer cell mitochondria.6—11 Besides, phosphonium salts themselves have a wide range of biological activities.12—18 The introduction of a methyl group into a 1,4-naphthoquinone molecule is known to change the reactivity of the latter. In some cases, the reactions proceed via a quinomethide intermediate and are often promoted by atmospheric oxygen.19—21 This chemical behavior of 2-methyl1,4-naphthoquinone (menadione, an analogue of vitamin K) would be observed in the reaction with triphenylphosphine. Previously, we have demonstrated that 1,2-naphthoquinones readily reacts with tertiary and secondary phosphines to form zwitterions with a P—C bond, which can serve as precursors for the synthesis of arylphosphonium salts.22,23 The phosphonium center was inserted into the starting 2-methyl-1,4-naphthoquinone using H-phosphonium salts.24 Here, we studied the reaction of menadione 1 with triphenylphosphine 2. This reaction, unlike the reaction of unsubstituted 1,4-naphthoquinone,25 occurs under mild conditions (dichloromethane, 20 C), but it is much slower (14 days, dry argon). The reaction in air at a reagent ratio of 1 : 3 proceeds much faster and addi-
* Subdivision of the Federal State Budgetary Institution of Science.
tionally affords triphenylphosphine oxide. In both reactions, the addition product of two triphenylphosphine molecules to one molecule of the starting diylide-type quinone 3 is generated as the major product (Scheme 1). One triphenylphosphine molecule is introduced at position 3 of menadione 1, while the second one is added at the methyl carbon atom. Therefore, menadione exhibits dual reactivity in the reaction with triphenylphosphine acting as both q
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