Scope of tetrazolo[1,5-a]quinoxalines in CuAAC reactions for the synthesis of triazoloquinoxalines, imidazoloquinoxalines, and rhenium complexes thereof

• Laura Holzhauer,
• Chloé Liagre,
• Olaf Fuhr,
• Nicole Jung and
• Stefan Bräse

Beilstein J. Org. Chem. 2022, 18, 1088–1099, doi:10.3762/bjoc.18.111

• ). Condensation to the corresponding quinoxalinone and subsequent chlorination was followed by introduction of the tetrazole moiety into the molecule via sodium azide to yield 11a–e. Alternatively, 4-chlorotetrazolo[1,5-a]quinoxaline (11f) was obtained after reaction of 2,3-dichloroquinoxaline (10f) with

Synthesis of pyrimido[1,6-a]quinoxalines via intermolecular trapping of thermally generated acyl(quinoxalin-2-yl)ketenes by Schiff bases

• Svetlana O. Kasatkina,
• Ekaterina E. Stepanova,
• Maksim V. Dmitriev,
• Ivan G. Mokrushin and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2018, 14, 1734–1742, doi:10.3762/bjoc.14.147

• contained only three types of products, and we succeeded to identify each of them. The structures of the reaction products were elucidated as the desired pyrimido[1,6-a]quinoxaline 3a, quinoxalinone 4a [29] and pyrido[1,2-a]quinoxaline 5a [29] (Scheme 2). Product IV of an alternative intermolecular trapping

• reaction (Table 1) was not detected. The most likely way of the formation of quinoxalinone 4a is hydration of the ketene with subsequent decarboxylation (Scheme 2); more careful drying the reaction vials and solvents easily reduced the amount of compound 4a. The formation of pyrido[1,2-a]quinoxaline 5a can

Mannich base-connected syntheses mediated by ortho-quinone methides

• Petra Barta,
• Ferenc Fülöp and
• István Szatmári

Beilstein J. Org. Chem. 2018, 14, 560–575, doi:10.3762/bjoc.14.43

• respect to the use of an enantiomeric cyclic imine in this type of reaction [83]. The formation of the possible naphthoxazino-quinoxalinone diastereomers 46 was investigated and studied by theoretical calculations (Scheme 5). In this and all previous cases, the conformational behaviour of the

Regiochemistry of cyclocondensation reactions in the synthesis of polyazaheterocycles

• Patrick T. Campos,
• Leticia V. Rodrigues,
• Andrei L. Belladona,
• Caroline R. Bender,
• Juliana S. Bitencurt,
• Fernanda A. Rosa,
• Davi F. Back,
• Helio G. Bonacorso,
• Nilo Zanatta,
• Clarissa P. Frizzo and
• Marcos A. P. Martins

Beilstein J. Org. Chem. 2017, 13, 257–266, doi:10.3762/bjoc.13.29

• ; quinoxalinone; thiazolo[3,2-a]pyrimidinone; Introduction Various syntheses of polyazaheterocycles are described in the literature because they are important components for the preparation of bioactive molecules [1][2][3]. One of the most important synthetic methods towards compounds containing nitrogen atoms

• of the most common approaches used for the synthesis of pyrazinones [9][10] and quinoxalinone [11][12] cores is the cyclocondensation reaction between 1,2-dicarbonyl compounds and 1,2-diamines. In this manner, Zamcova et al. [13] reported the synthesis of imidazo[1,2]heteroarylglyoxylates, which

• involved the cyclocondensation of 1,2-dicarbonyl compounds with ethylenediamine and 1,2-phenylenediamine and they obtained polyazaheterocycles with pyrazinone and quinoxalinone cores. Although there is a wide range of papers reporting on cyclocondensation reactions, only few authors have discussed the

A novel method for heterocyclic amide–thioamide transformations

• Walid Fathalla,
• Ibrahim A. I. Ali and
• Pavel Pazdera

Beilstein J. Org. Chem. 2017, 13, 174–181, doi:10.3762/bjoc.13.20

• cyclohexylammonium salt (2). The two-step thiation of quinazolin-4-one A1–6 and phthalazin-1-ones A7 and A8. Thiation of quinoline A9 and quinoxalinone A10–13. Rational mechanism of the reaction of 4-chloro-2-phenylquinazoline (B2) to 2-phenylquinazolin-4(3H)-thione. Synthesis of quinazolin-4-thionesa. Synthesis of