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

• ; 1,4-benzothiazine; cyclocondensation; diversity-oriented synthesis; furan-2,3-dione; Introduction Enaminones fused to the 1,4-benzoxazine-2-one I or quinoxaline-2(1H)-one II moiety (Figure 1) represent an intensively investigated class of enamines. Undying interest in these compounds is due to the

From dipivaloylketene to tetraoxaadamantanes

• Gert Kollenz and
• Curt Wentrup

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

• obtained by flash vacuum pyrolysis of furan-2,3-dione 6 and dimerizes to 1,3-dioxin-4-one 3, which is a stable but reactive ketene. The transannular addition and rearrangement of enols formed by the addition of nucleophiles to the ketene function in 3 generates axially chiral 2,6,9-trioxabicyclo[3.3.1

• dimerization of dipivaloylketene (2), itself obtained in high yield by FVP of furan-2,3-dione 6 (Scheme 3). Ketene 3 reacts with a variety of nucleophiles in an addition reaction to the ketene function, thereby transforming the ketene to enol derivatives 14 or 9 of 1,3-dioxin-4-ones. Subsequently, these enols

Switchable highly regioselective synthesis of 3,4-dihydroquinoxalin-2(1H)ones from o-phenylenediamines and aroylpyruvates

• Juraj Dobiaš,
• Marek Ondruš,
• Gabriela Addová and
• Andrej Boháč

Beilstein J. Org. Chem. 2017, 13, 1350–1360, doi:10.3762/bjoc.13.132

• -amino group of 11e. The opposite regioisomer 17e (ANTI) was selectively prepared by reaction of the more nucleophilic m-amino group of 11e with the most reactive lactonic carbonyl group in 5-(4-chlorophenyl)furan-2,3-dione (13) through an amide intermediate 15 (Scheme 2). Abasolo et al. studied the

• ) (natively preferring SYN regioselectivity, see Table 1, entry 4, column 3) complicated the desired reaction. The other possibility was to perform the regioselective synthesis of 17d (ANTI) from an appropriate furan-2,3-dione 13 (Scheme 2). The preparation of 13 failed in our hands. Therefore, we decided to

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

• -azabicyclo[4.4.1]undeca-3,8-diene) derivatives of 4,11-dioxa-1,8-diazatricyclo[8.4.0.03,8]tetradeca-5,12-diene, a new heterocyclic system, were formed. Boiling a benzene solution of furan-2,3-dione 1a and azirine 2a (1:1) for 0.5 h gave a mixture of compounds 3a–5a, which were isolated by column

• chromatography (Scheme 1). To find the optimal reaction conditions a series of experiments was performed with furan-2,3-dione 1a and azirine 2a in different solvents (benzene, toluene, cyclohexane, THF, nitromethane) monitoring the reaction by 1H NMR using 1-methylnaphthalene as internal standard. 1H NMR spectra

• with azirine 2a. Reactions of compounds 3d and 18a with methanol. Yields of products of the reaction of furan-2,3-dione 1a and azirine 2a in boiling benzene solution for 0.5 h according to 1H NMR. Products of the reactions of azirines 2a–c and furandiones 1a–c. Supporting Information Detailed