Different regiochemical outcomes in annulation reactions of pyridine-2-sulfenyl chloride with phenyl vinyl chalcogenides
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Different regiochemical outcomes in annulation reactions of pyridine-2-sulfenyl chloride with phenyl vinyl chalcogenides and allyl phenyl chalcogenides Vladimir A. Potapov1*, Roman S. Ishigeev1, Irina V. Shkurchenko1,2, Svetlana V. Amosova1 1
Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, 1 Favorsky St., Irkutsk 664033, Russia; e-mail: [email protected] 2 Pedagogical Institute of Irkutsk State University, 6 Nizhnyaja Naberezhnaya St., Irkutsk 664003, Russia Submitted June 24, 2020 Accepted after revision August 3, 2020
Translated from Khimiya Geterotsiklicheskikh Soedinenii, 2020, 56(9), 1226–1229
Annulation reactions of pyridine-2-sulfenyl chloride with phenyl vinyl chalcogenides and allyl phenyl chalcogenides proceeded regioselectively, but with different regiochemical outcomes and led to the formation of new 2- and 3-substituted [1,3]thiazolo[3,2-a]pyridinium derivatives in 90–100% yields. Keywords: allyl phenyl chalcogenides, 2,2'-disulfandiyldipyridine, phenyl vinyl chalcogenides, pyridine-2-sulfenyl chloride, [1,3]thiazolo[3,2-a]pyridine derivatives.
Thiazolo[3,2-a]pyridines represent an important class of organic compounds containing two fused heterocyclic moieties and have been characterized with respect to various types of biological activity.1–4 Some of these compounds exhibited antibacterial,1 anticancer, or antitrichomonas activity,2 as well as have been shown to act as α-glucosidase3 and RNA polymerase inhibitors.4 It is important to continue the efforts directed toward the synthesis of previously unknown heterocyclic compounds containing promising pharmacophoric motifs and functional groups deemed capable of further transformations. One of the directions applicable to the synthesis of thiazolo[3,2-a]pyridine derivatives is based on the interaction of pyridine-2-sulfenyl chloride with unsaturated compounds.5–8 We have been developing effective synthetic approaches for the annulation of 1,3-thiazole and 1,3-selenazole rings to pyridine ring via the reactions of pyridine-2-sulfenyl and pyridine-2-selenenyl halides with functionalized alkenes.6–8 The reactions of pyridine-2-sulfenyl and pyridine2-selenenyl halides with divinyl sulfide and divinyl selenide provided access to [1,3]thiazolo[3,2-a]pyridine derivatives 0009-3122/20/56(9)-1226©2020 Springer Science+Business Media, LLC
containing a vinylchalcogenide group.7 These reactions were the first examples showing the addition–annulation of pyridine-2-chalcogenyl halides to vinylsulfanyl and vinylselanyl groups. However, the reactions of pyridine2-sulfenyl halides with phenyl vinyl and alkyl vinyl sulfides and selenides have not been described in the literature. Also, there are no precedents known for the reactions of pyridine-2-sulfenyl halides with allyl sulfides, allyl selenides, and allyl ethers. In this work, we studied the reactions of pyridine2-sulfenyl chloride (1) with vinyl and allyl chalcogenides: phenyl vinyl ether (2а), phenyl vinyl sulfide (2b), phenyl vinyl selenide (2c), allyl phenyl ether
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