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

• targeted cancer therapy development. Keywords: 1,4-benzothiazine; 1,3-benzothiazole; 1H-pyrrole-2,3-diones; nitrogen heterocycle; sulfur heterocycle; Introduction Pyrrolo[2,1-b][1,3]benzothiazole (PBTA) is an angularly fused sulfur and nitrogen-containing heterocyclic scaffold. Its derivatives are

• ] and reactions of 3-acyl-2,3-dihydro-1,3-benzothiazole-2-carbonitriles with acetylenedicarboxylate (Scheme 1, entry 9) [4]. The second group of approaches to the PBTA scaffold is an annulation of o-aminothiophenol with a pyrrolothiazole moiety (Scheme 2). It includes catalytic cascade reactions of o

• 1 (Scheme 5). Firstly, FPDs 1 bear a 1,4-benzothiazine moiety that is known to be prone to undergo a ring contraction reaction to afford the corresponding 1,3-benzothiazole derivatives under the action of nucleophiles [39][40][41][42], oxidizing agents [43][44][45][46][47][48] or ultraviolet

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

• the catalyst SiO2@H3PW12O40 [21], the reaction of tetracarbonyl compounds with o-aminothiophenol (1a) [22][23], the reaction of copper(II) chelate of ethyl pentafluorobenzoylpyruvate with o-aminothiophenol (1a, one example) [24] and the reaction of DMAD with 6-nitro-1,3-benzothiazole (one example) [25

Economical and scalable synthesis of 6-amino-2-cyanobenzothiazole

• Jacob R. Hauser,
• Hester A. Beard,
• Mary E. Bayana,
• Katherine E. Jolley,
• Stuart L. Warriner and
• Robin S. Bon

Beilstein J. Org. Chem. 2016, 12, 2019–2025, doi:10.3762/bjoc.12.189

• ) connected to a 20 mL disposable syringe with an 8 inch, 16 gauge Luer fitting syringe needle. Reaction procedures 2-Chloro-6-nitro-1,3-benzothiazole (6) [15][20] 2-Chloro-1,3-benzothiazole (16, 10.0 g, 58.95 mmol) was added portion wise to concentrated H2SO4 (60 mL) in a cooled round-bottomed flask (ice

• –194 °C (EtOH); 1H NMR (500 MHz, CDCl3) δ 8.75 (d, J = 2.3 Hz, 1H, CH-7), 8.38 (dd, J = 9.0, 2.3 Hz, 1H, CH-5), 8.07 (d, J = 9.0 Hz, 1H, CH-4); 13C NMR (125 MHz, CDCl3) δ 158.9 (C-2), 154.9 (C-6), 145.6 (C-7a), 136.6 (C-3a), 123.5 (CH-4), 122.4 (CH-5), 117.8 (CH-7). 6-Nitro-1,3-benzothiazole-2

• -carbonitrile (13) [19] A solution of NaCN (2.40 g, 48.97 mmol) in H2O (100 mL) was added slowly to a stirred solution of 2-chloro-6-nitro-1,3-benzothiazole (6, 10.0 g, 46.59 mmol) and DABCO (748 mg, 6.99 mmol) in MeCN (1000 mL). The reaction mixture was stirred at room temperature for 24 h. Excess cyanide was

Amyloid-β probes: Review of structure–activity and brain-kinetics relationships

• Todd J. Eckroat,
• Abdelrahman S. Mayhoub and
• Sylvie Garneau-Tsodikova

Beilstein J. Org. Chem. 2013, 9, 1012–1044, doi:10.3762/bjoc.9.116

• was coupled with 2-(4-aminophenyl)-1,3-benzothiazole (92) (prepared from 2-aminothiophenol (66) and 4-aminobenzoic acid (93)) by using EDCI·HCl and HOBt (Scheme 7C) [69]. Deprotection followed by reaction with the [Re] or [99mTc] precursors gave 84a and 84b. While both 83a and 84a showed promise as in

Synthesis of 2,3-dihydronaphtho[2,3-d][1,3]thiazole-4,9-diones and 2,3-dihydroanthra[2,3-d][1,3]thiazole-4,11-diones and novel ring contraction and fusion reaction of 3H-spiro[1,3-thiazole-2,1'-cyclohexanes] into 2,3,4,5-tetrahydro-1H-carbazole-6,11-diones

• Lidia S. Konstantinova,
• Kirill A. Lysov,
• Ljudmila I. Souvorova and
• Oleg A. Rakitin

Beilstein J. Org. Chem. 2013, 9, 577–584, doi:10.3762/bjoc.9.62

• , there exists only a single example of the thiazole conversion to thiazole-2-thione, i.e., heating of 3-methyl-2,3-dihydro-1,3-benzothiazole with elemental sulfur at 200 °C for 0.5 h giving 3-methyl-1,3-benzothiazole-2(3H)-thione [17]. We described a similar conversion of the methylene group to