Synthesis of 1,4-benzothiazinones from acylpyruvic acids or furan-2,3-diones and o-aminothiophenol

• Ekaterina E. Stepanova,
• Maksim V. Dmitriev and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2020, 16, 2322–2331, doi:10.3762/bjoc.16.193

• 2019499, Scheme 5). The acid 2a reacted with a carbodiimide to form the reactive isourea derivative X which underwent intramolecular cyclization with the formation of furandione 5a which reacted with o-aminothiophenol (1a). Product 3a was formed when the o-aminothiophenol’s SH group attacked the compound

• the suspension of acid 2a with DCC, formation of the white precipitate of dicyclohexylurea was observed, which gave the evidence of intramolecular cyclization to furandione 5a with dicyclohexylurea elimination occurring. The formation of furandione 5a explained well our observations when DMAP was used

• as an additive (Table 1, entry 29), since furandiones 5 are well-known to readily react with amines to afford various products [33]. To confirm our assumption, we examined the reaction of furandione 5a with DMAP. For this, equimolar amounts of compound 5a and DMAP were stirred at room temperature in

Synthesis and highly efficient light-induced rearrangements of diphenylmethylene(2-benzo[b]thienyl)fulgides and fulgimides

• Vladimir P. Rybalkin,
• Sofiya Yu. Zmeeva,
• Lidiya L. Popova,
• Valerii V. Tkachev,
• Andrey N. Utenyshev,
• Olga Yu. Karlutova,
• Alexander D. Dubonosov,
• Vladimir A. Bren,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2020, 16, 1820–1829, doi:10.3762/bjoc.16.149

• heterocyclic aldehydes or ketones with methylene succinates followed by subsequent hydrolysis and dehydration processes. Under exposure of solutions or crystals of thus prepared hetaryl(aryl)-substituted dihydrofuran-2,5-diones to UV light, those bearing an isopropylidene fragment attached to the furandione

From dipivaloylketene to tetraoxaadamantanes

• Gert Kollenz and
• Curt Wentrup

Beilstein J. Org. Chem. 2018, 14, 1–10, doi:10.3762/bjoc.14.1

• of compounds 5 containing functional groups is accessible (Scheme 2). In this review we will start with an overview of the syntheses and chemistry of the bisdioxines leading on to the syntheses of tetraoxaadamantanes. Review Bisdioxines The synthesis of bisdioxines 8–13 starts with furandione 6

Domino reactions of 2H-azirines with acylketenes from furan-2,3-diones: Competition between the formation of ortho-fused and bridged heterocyclic systems

• Alexander F. Khlebnikov,
• Mikhail S. Novikov,
• Viktoriia V. Pakalnis,
• Roman O. Iakovenko and
• Dmitry S. Yufit

Beilstein J. Org. Chem. 2014, 10, 784–793, doi:10.3762/bjoc.10.74

• : acylketene; azirine; domino reaction; furandione; Introduction 2H-Azirines, the most strained nitrogen unsaturated heterocyclic systems, are versatile building blocks for the construction of various heterocyclic nitrogen-containing compounds. Because 2H-azirines contain an activated C=N double bond and a

• give only 1:2 adducts 3. These were easily isolated from the reaction mixtures by crystallization. In reactions of 1a with 2b, 1b with 2b, and 1c with 2a only 2:2 adducts 4 and 5 are formed and were isolated by chromatography. Thermolysis of furandione 1c in the presence of azirine 2b led to tarring

• stored under the same conditions but without addition of K2CO3 completely transformed into 2,5-diphenylpyrazine. The reaction of 2-phenyl-substituted azirine 2d with furandione 1a leads, obviously due to steric reasons, to formation of only the exo-monoadduct 17 (Scheme 5). The structure of compound 17