Non-covalent organocatalyzed enantioselective cyclization reactions of α,β-unsaturated imines

• Sergio Torres-Oya and
• Mercedes Zurro

Beilstein J. Org. Chem. 2024, 20, 3221–3255, doi:10.3762/bjoc.20.268

• isocyanide carbon, behaves a C3 synthon affording benzo[d]isothiazole 1,1-dioxide-dihydropyrroles 27 bearing two adjacent stereocenters in high yields (27–98%) and with moderate to excellent stereoselectivities (54–97% ee) when using thiourea IX (Scheme 10). The cyclization was observed with all derivatives

Synthesis and biological profile of 2,3-dihydro[1,3]thiazolo[4,5-b]pyridines, a novel class of acyl-ACP thioesterase inhibitors

• Jens Frackenpohl,
• David M. Barber,
• Guido Bojack,
• Birgit Bollenbach-Wahl,
• Ralf Braun,
• Rahel Getachew,
• Sabine Hohmann,
• Kwang-Yoon Ko,
• Karoline Kurowski,
• Bernd Laber,
• Rebecca L. Mattison,
• Thomas Müller,
• Anna M. Reingruber,
• Dirk Schmutzler and
• Andrea Svejda

Beilstein J. Org. Chem. 2024, 20, 540–551, doi:10.3762/bjoc.20.46

• 1,8-naphthyridine scaffold can also be formally substituted by an isothiazole group, as can be seen in isothiazolo[3,4-b]pyridine 6 [15]. Thus, several bicyclic heteroaromatic motifs containing two nitrogen atoms serve as structural surrogates of cinmethylin (1), bearing a substituted 7-oxabicyclo

Synthesis of spiropyridazine-benzosultams by the [4 + 2] annulation reaction of 3-substituted benzoisothiazole 1,1-dioxides with 1,2-diaza-1,3-dienes

• Wenqing Hao,
• Long Wang,
• Jinlei Zhang,
• Dawei Teng and
• Guorui Cao

Beilstein J. Org. Chem. 2024, 20, 280–286, doi:10.3762/bjoc.20.29

• benzoisothiazole 1,1-dioxides with 1,2-diaza-1,3-dienes (Scheme 1). Results and Discussion To initiate our studies, 3-ethylbenzo[d]isothiazole 1,1-dioxide (1a) and α-halogeno hydrazone 2a were selected as the model substrates. Our aim was to explore the possibility of enamine–iminium tautomerism of N-sulfonyl

• reaction of 3-ethylbenzo[d]isothiazole 1,1-dioxide (1a, 1.0 g) and α-halogeno hydrazone 2a (2.1 g) afforded 3aa (2.0 g) in 91% yield (Scheme 3) [34]. Finally, we focused on the transformation of 3aa. When 3aa was treated with KOH and H2O in methanol at 60 °C, the 3,3-disubsitituted-1,2-benzothiazin-4-one

• bond under basic conditions. Finally, the ring expansion led to intermediate C which was then hydrolyzed to 4aa. Conclusion In conclusion, we have developed a [4 + 2] annulation reaction of 3-substituted benzo[d]isothiazole 1,1-dioxides with 1,2-diaza-1,3-dienes for the efficient preparation of

Development of N-F fluorinating agents and their fluorinations: Historical perspective

• Teruo Umemoto,
• Yuhao Yang and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2021, 17, 1752–1813, doi:10.3762/bjoc.17.123

• reagent 27-2 in good to high yields [90]. In addition, Takeuchi et al. reported that optically active N-fluorosultams, (R)- and (S)-N-fluoro-3-cyclohexyl-3-methyl-2,3-dihydrobenzo[1,2-d]isothiazole 1,1-dioxides 27-6 (Scheme 61) were efficient reagents for the asymmetric fluorination of enolates [91]. To

Synthesis of benzannelated sultams by intramolecular Pd-catalyzed arylation of tertiary sulfonamides

• Valentin A. Rassadin,
• Mirko Scholz,
• Anastasiia A. Klochkova,
• Armin de Meijere and
• Victor V. Sokolov

Beilstein J. Org. Chem. 2017, 13, 1932–1939, doi:10.3762/bjoc.13.187

• spectrometric data. The structure of the sultam 10c was unequivocally confirmed by a single-crystal X-ray diffraction study (Figure 1). While the intramolecular arylation of the C–H acidic CH2 group in sulfamoylacetates 8a–g to yield 1,3-dihydrobenzo[c]isothiazole-2,2-dioxide derivatives 10a–h works well, the

• (PMB) from the nitrogen, the methyl 1-(4-methoxybenzyl)-1,3-dihydrobenzo[c]isothiazole-3-carboxylate-2,2-dioxide (10a) was treated with cerium(IV) ammonium nitrate (CAN) according to a previously developed protocol [18][20]. Unexpectedly, this PMB resisted its removal, and the only formed product was

• methyl 5-chloro-1-(4-methoxybenzyl)-1,3-dihydrobenzo[c]isothiazole-3-carboxylate-2,2-dioxide (10c) in the crystal [CCDC: 1520988]. Structure of methyl 1-(4-methoxybenzyl)-3-(nitrooxy)-1,3-dihydrobenzo[c]isothiazole-3-carboxylate-2,2-dioxide (22) in the crystal [CCDC: 1520989]. A previous and a new

Synthesis of alkynyl-substituted camphor derivatives and their use in the preparation of paclitaxel-related compounds

• M. Fernanda N. N. Carvalho,
• Rudolf Herrmann and
• Gabriele Wagner

Beilstein J. Org. Chem. 2017, 13, 1230–1238, doi:10.3762/bjoc.13.122

• positions. In addition, where taxol has the bridgehead hydroxy and its neighbouring benzoate groups, we find the heterocyclic reduced isothiazole ring in the product of the Pt(II) catalysis. Other camphor derivatives prepared as entrance to taxoid compounds have a carbocyclic ring at this place in the

Strecker degradation of amino acids promoted by a camphor-derived sulfonamide

• M. Fernanda N. N. Carvalho,
• M. João Ferreira,
• Ana S. O. Knittel,
• Maria da Conceição Oliveira,
• João Costa Pessoa,
• Rudolf Herrmann and
• Gabriele Wagner

Beilstein J. Org. Chem. 2016, 12, 732–744, doi:10.3762/bjoc.12.73

• was stirred at 45 °C for ca. 10 h. Compound 2 ((3aS,6S,Z)-7-(((3aS,6S)-8,8-dimethyl-2,2-dioxido-4,5,6,7-tetrahydro-3H-3a,6-methanobenzo[c]isothiazol-7-yl)imino)-8,8-dimethyl-4,5,6,7-tetrahydro-3H-3a,6-methanobenzo[c]isothiazole 2,2-dioxide) was obtained as a pale yellow solid upon filtration and

Isoxazolium N-ylides and 1-oxa-5-azahexa-1,3,5-trienes on the way from isoxazoles to 2H-1,3-oxazines

• Alexander F. Khlebnikov,
• Mikhail S. Novikov,
• Yelizaveta G. Gorbunova,
• Ekaterina E. Galenko,
• Kirill I. Mikhailov,
• Viktoriia V. Pakalnis and
• Margarita S. Avdontceva

Beilstein J. Org. Chem. 2014, 10, 1896–1905, doi:10.3762/bjoc.10.197

• Manning [4][5] discovered the Rh-catalyzed reaction of diazo esters with 3,5-dialkylisoxazoles, benzo[d]isoxazole and 3-chlorobenzo[d]isothiazole leading to the corresponding 2H-1,3-oxazines, 2H-benzo[e][1,3]oxazine and 2H-benzo[e][1,3]thiazine. The authors assumed that the reaction of isoxazoles A with

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

• pyridine containing lead compounds is to commonly replace the ring with a bioisostere such as a methylisoxazole, isothiazole, oxadiazole [11][12] or various diazines [13][14]. This strategy is based mainly upon a desire to avoid potential late stage toxicology issues which as indicated have arisen in the

Chemistry of polyhalogenated nitrobutadienes, 10: Synthesis of highly functionalized heterocycles with a rigid 6-amino-3-azabicyclo[3.1.0]hexane moiety

• Viktor A. Zapol’skii,
• Jan C. Namyslo,
• Armin de Meijere and
• Dieter E. Kaufmann

Beilstein J. Org. Chem. 2012, 8, 621–628, doi:10.3762/bjoc.8.69

• feasible. Keywords: isothiazole; nitrochlorobutadiene; nitropyrazole; nucleophilic substitution; pyrimidine; small rings; Introduction Nitropolychlorobutadienes are potent precursors for a variety of highly functionalized acyclic and (hetero)cyclic compounds. The readily accessible 2-nitroperchloro-1,3

• nucleophilic substitution reactions as described above, it was of interest to incorporate a persubstituted diene unit as in 3 and 4 into a heterocycle. For example, the isothiazole 17 was obtained from the nitrodiene 3 upon treatment with elemental sulfur at 200 °C [23]. Subsequent reaction with fuming nitric

• , 12. Synthesis of the 4,4-bis(aminoazabicyclo[3.1.0]hexyl)-1-chloro-1,3-dinitrobutadiene 13. Synthesis of the highly substituted trisaminodichloronitrobutadiene 16. Syntheses of the perfunctionalized isothiazole derivatives 20, 21. Preparation of the pyrazoles 27, 28, the pyrimidine 26 and the

Approaches towards the synthesis of 5-aminopyrazoles

• Ranjana Aggarwal,
• Vinod Kumar,
• Rajiv Kumar and
• Shiv P. Singh

Beilstein J. Org. Chem. 2011, 7, 179–197, doi:10.3762/bjoc.7.25

• sodium ethoxide (Scheme 47). Ioannidou and Koutentis [91] investigated the conversion of isothiazoles into pyrazoles on treatment with hydrazine. The influence of various C-3, C-4 and C-5 isothiazole substituents and some limitations of this ring transformation were investigated. When a good nucleofugal

• group (e.g., Cl, Br and I) is present at C-3 in the isothiazole 165, it is replaced by an amino group and 5-aminopyrazoles 166 are obtained. However, when the 3-substituent is not a good leaving group it is retained in the pyrazole product 167. A series of 3-chloro-5-substituted isothiazole-4

• -carbonitriles 168 bearing steric and/or electronic constraints at C-5 were also treated with anhydrous hydrazine and the corresponding 3-aminopyrazoles 169 were obtained in varying yields. However, when the substituent at C-5 in isothiazole was a better nucleofuge (e.g., PhO, PhS and Cl), the 5