Synthesis, characterization, antimicrobial, cytotoxic and carbonic anhydrase inhibition activities of multifunctional pyrazolo-1,2-benzothiazine acetamides

• Ayesha Saeed,
• Shahana Ehsan,
• Muhammad Zia-ur-Rehman,
• Erin M. Marshall,
• Sandra Loesgen,
• Abdus Saleem,
• Simone Giovannuzzi and
• Claudiu T. Supuran

Beilstein J. Org. Chem. 2025, 21, 348–357, doi:10.3762/bjoc.21.25

• prepared scaffolds are valuable additions to the class of pyrazolo-1,2-benzothiazine antibiotics with selective antistaphylococcal activity. Keywords: acetamides; antibiotics; antimicrobial; benzothiazines; Staphylococcus aureus; Introduction The global crisis of antibiotic resistance has been

• work covers the synthesis of synergistic scaffolds containing biologically active 1,2-benzothiazine, pyrazole, and amide moieties. 1,2-Benzothiazines are chemically gifted drug candidates. Since one of the very first synthesis in 1956 [11], these scaffolds have proved themselves as versatile and

• biologically active useful candidates. NSAIDs (non-steroidal anti-inflammatory drugs) currently approved like piroxicam [12], meloxicam [13], and other derivatives of these two are well known for their activities [5]. 1,2-Benzothiazines are highly bioactive moieties and have been explored as antibacterial [14

Nucleophile-induced ring contraction in pyrrolo[2,1-c][1,4]benzothiazines: access to pyrrolo[2,1-b][1,3]benzothiazoles

• Ekaterina A. Lystsova,
• Maksim V. Dmitriev,
• Andrey N. Maslivets and
• Ekaterina E. Khramtsova

Beilstein J. Org. Chem. 2023, 19, 646–657, doi:10.3762/bjoc.19.46

• » conditions (Scheme 4, entry 15) [10][11]. This work reports a new approach to PBTA derivatives via nucleophile-induced ring contraction in pyrrolo[2,1-c][1,4]benzothiazines 1 (Scheme 5, entry 16), which can generally be attributed as a new entry to the fourth group of approaches to the PBTA scaffold (Scheme

• reaction in 1-(2-bromophenyl)-5-(butylsulfanyl)pyrrolidin-2-one. Approach to PBTAs via intramolecular cyclizations of 1-(2-thiophenyl)pyrroles. A new approach to PBTAs via nucleophile-induced ring contraction in pyrrolo[2,1-c][1,4]benzothiazines. Reaction of APBTT 1a with methanol (2a). Derivatization of

Derivatives of benzo-1,4-thiazine-3-carboxylic acid and the corresponding amino acid conjugates

• Péter Kisszékelyi,
• Tibor Peňaška,
• Klára Stankovianska,
• Mária Mečiarová and
• Radovan Šebesta

Beilstein J. Org. Chem. 2022, 18, 1195–1202, doi:10.3762/bjoc.18.124

• isolated. Moreover, the coupling of benzothiazines with amino acids was realized. In doing so, an enantioselective synthesis of the nonproteinogenic amino acid 2-amino-3-propylhexanoic acid was accomplished. Keywords: amino acid; benzothiazine; oxidative dimerization; peptide coupling; stereoselective

• formed in situ from the corresponding aminothiols [9][10][11][12][13]. Green chemistry methods for benzo-1,4-thiazine synthesis have also been described in the literature. 2,3-Disubstituted-1,4-benzothiazines were prepared in high yield (83–96%) by oxidative cyclocondensation of 2-aminobenzenethiols and

• different temperatures under classical conditions and even under MWI (Table 1, entries 12 and 13). Also, reactions with 6,6'-disulfanediylbis(3-methoxyaniline) were unsuccessful. Having observed dimer formation during the syntheses of benzothiazines, we have attempted to synthesize the corresponding dimer

New efficient synthesis of polysubstituted 3,4-dihydroquinazolines and 4H-3,1-benzothiazines through a Passerini/Staudinger/aza-Wittig/addition/nucleophilic substitution sequence

• Long Zhao,
• Mao-Lin Yang,
• Min Liu and
• Ming-Wu Ding

Beilstein J. Org. Chem. 2022, 18, 286–292, doi:10.3762/bjoc.18.32

• Abstract A new efficient synthesis of polysubstituted 3,4-dihydroquinazolines and 4H-3,1-benzothiazines via sequential Passerini/Staudinger/aza-Wittig/addition/nucleophilic substitution reaction has been developed. The three-component Passerini reactions of 2-azidobenzaldehydes 1, benzoic acid (2), and

• isocyanides 3 produced the azide intermediates 4, which were treated sequentially with triphenylphosphine, isocyanates (or CS2), and secondary amines to give polysubstituted 3,4-dihydroquinazolines 8 and 4H-3,1-benzothiazines 11 in good overall yields through consecutive Passerini/Staudinger/aza-Wittig

• /addition/nucleophilic substitution reactions. Keywords: aza-Wittig reaction; 3,4-dihydroquinazoline; 4H-3,1-benzothiazine; nucleophilic substitution; Passerini reaction; Staudinger reaction; Introduction The chemistry of 3,4-dihydroquinazolines and 4H-3,1-benzothiazines is of constant interest owing to

On the functionalization of benzo[e][2,1]thiazine

• Kirill Popov,
• Tatyana Volovnenko and
• Julian Volovenko

Beilstein J. Org. Chem. 2009, 5, No. 42, doi:10.3762/bjoc.5.42

• with a view to improving benzothiazine-based drugs and to avoid the adverse effects [6][7]. In previous work [8][9] we reported the synthesis of some novel benzothiazines, in particular benzo[e][2,1]thiazine derivatives, the β-chloroaldehydes 1 and β-chloronitriles 2 (Figure 1); their chemistry was