Synthesis and Heterocyclization of 4-(Alkenylsulfanyl)quinazolines
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hesis and Heterocyclization of 4-(Alkenylsulfanyl)quinazolines E. I. Bakhteevaa,*, D. G. Kima, and V. V. Sharutina a
South Ural State University, Chelyabinsk, 454080 Russia *e-mail: [email protected]
Received November 19, 2019; revised June 10, 2020; accepted June 13, 2020
Abstract—Alkylation of quinazoline-4(3H)-thione with 3-chloro-2-methylpropene and 2,3-dibromopropene afforded previously unknown 4-[(2-methylprop-2-en-1-yl)sulfanyl]quinazoline and 4-[(2-bromoprop-2-en-1yl)sulfanyl]quinazoline, respectively. 4-[(Prop-2-en-1-yl)sulfanyl]quinazoline reacted with bromine to give bromocyclization product and product of bromine addition to the exocyclic double bond. The reaction of 4-[(2-methylprop-2-en-1-yl)sulfanyl]quinazoline with halogens involved thiazole ring fusion. 5-Bromo-3methylidene-2,3-dihydro[1,3]thiazolo[3,2-c]quinazolinium bromide was isolated in the reaction of 4-[(2-bromoprop-2-en-1-yl)sulfanyl]quinazoline with bromine, and the reaction of the same substrate with iodine gave a mixture of 3-bromo-3-iodomethyl-2,3-dihydro[1,3]thiazolo[3,2-c]quinazolinium and 3-methylidene-2,3-dihydro[1,3]thiazolo[3,2-c]quinazolinium iodides. 4-[(2-Methylprop-2-en-1-yl)sulfanyl]quinazoline reacted with 2 equiv of iodine to produce 3-methyl-3-iodomethyl-2,3-dihydro[1,3]thiazolo[3,2-c]quinazolinium triiodide and pentaiodide; the structure of the latter was studied by X-ray diffraction. Keywords: quinazoline-4(3H)-thione, 4-(allylsulfanyl)quinazoline, 4-(methallylsulfanyl)quinazoline, 4-[(2-bromoprop-2-en-1-yl)sulfanyl]quinazoline, [1,3]thiazolo[3,2-c]quinazoline, alkenylation, halocyclization, X-ray analysis
DOI: 10.1134/S1070428020090018 Quinazoline ring system is a key structural fragment of many natural and synthetic biologically active molecules which exhibit antiallergic, antihypertensive, antimicrobial, antifungal, antitubercular, anticonvulsant, and sedative activities [1–3]. However, there are only a few published data on the synthesis and properties of dihydrothiazoloquinazolinium systems. These compounds can be obtained by heterocyclization of S-alkenyl derivatives of quinazoline-4(3H)-thione by the action of halogens. For instance, bromocyclization of 2-aryl-4-(allylsulfanyl)quinazolines and iodocyclization of 4-(allylsulfanyl)quinazoline have been reported to produce thiazolo[2,3-c]quinazolinium derivatives [4–7]. The goal of the present work was to synthesize new 4-(alkenylsulfanyl)quinazolines and study their reactions with halogens. Quinazoline-4(3H)-thione (1) is known to react with allyl bromide (2a) in acetone in the presence of potassium carbonate [8], in cyclohexane in the presence of tetrabutylammonium bromide and potassium hydroxide [9], and in propan-2-ol in the presence of
potassium hydroxide [7] to give 4-(allylsulfanyl)quinazoline (3a). We reacted quinazoline-4(3H)-thione with 3-chloro-2-methylpropene (2b) and 2,3-dibromopropene (2c) in propan-2-ol or in aqueous alcohol in the presence of potassium hydroxide and isolated previously unknown 4-[(2-methylprop-2-en-1-yl)sulfanyl]quinazoline (3b) an
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