Lewis acid-promoted direct synthesis of isoxazole derivatives

• Dengxu Qiu,
• Chenhui Jiang,
• Pan Gao and
• Yu Yuan

Beilstein J. Org. Chem. 2023, 19, 1562–1567, doi:10.3762/bjoc.19.113

• Dengxu Qiu Chenhui Jiang Pan Gao Yu Yuan College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002, China 10.3762/bjoc.19.113 Abstract Isoxazole derivatives were synthesized via a one-pot method utilizing 2-methylquinoline derivatives as template substrates, sodium

• nitrite as a nitrogen-oxygen source, and solely using aluminum trichloride as the additive. This approach circumvents the need for costly or highly toxic transition metals and presents a novel pathway for the synthesis of isoxazole derivatives. Keywords: aluminum trichloride; Lewis acid; isoxazole

• derivatives; sodium nitrite; transition metals; Introduction The isoxazole derivatives not only exist in many natural products [1][2][3] and pharmaceutical intermediates [4][5][6][7], but also have great application values in organic synthesis [8][9] (Figure 1). In the past decades, many methods have been

A straightforward conversion of 1,4-quinones into polycyclic pyrazoles via [3 + 2]-cycloaddition with fluorinated nitrile imines

• Greta Utecht-Jarzyńska,
• Karolina Nagła,
• Grzegorz Mlostoń,
• Heinz Heimgartner,
• Marcin Palusiak and
• Marcin Jasiński

Beilstein J. Org. Chem. 2021, 17, 1509–1517, doi:10.3762/bjoc.17.108

• -quinones, competitive reaction courses involving either ethylenic C=C or carbonyl C=O bonds were observed. For example, the more polar arylnitrile oxides and 1,4-benzoquinones reacted via addition to the C=C bond to give fused isoxazole derivatives [10][11][12] as well as with the C=O bond yielding

The use of isoxazoline and isoxazole scaffolding in the design of novel thiourea and amide liquid-crystalline compounds

• Itamar L. Gonçalves,
• Rafaela R. da Rosa,
• Vera L. Eifler-Lima and
• Aloir A. Merlo

Beilstein J. Org. Chem. 2020, 16, 175–184, doi:10.3762/bjoc.16.20

• , isoxazoline derivatives induce the formation of an SmA mesophase by lateral diffusion, while isoxazole derivatives favor the formation of a nematic mesophase by longitudinal diffusion, along SmA mesophase [27]. In addition, for amide 19, a second smectic mesophase was identified by POM as the monotropic SmC

• temperature. The SmA mesophase was predominant for both thioureas and amides and the nematic mesophase was observed only for thioureas and amides containing the isoxazole ring. The mesophase range was dependent on the nature of the 5-membered heterocycle. The isoxazole derivatives showed a larger mesophase

Transition-metal-free [3 + 3] annulation of indol-2-ylmethyl carbanions to nitroarenes. A novel synthesis of indolo[3,2-b]quinolines (quindolines)

• Michał Nowacki and
• Krzysztof Wojciechowski

Beilstein J. Org. Chem. 2018, 14, 194–202, doi:10.3762/bjoc.14.14

• construction of the quindoline system. Synthesis of condensed pyridines mediated by a σH-adduct. Formation of condensed isoxazole derivatives. Reaction of unprotected indole ester 1c with 4-chloronitrobenzene. A plausible mechanism for the formation of 11-(phenylsulfonyl)indolo[3,2-b]quinolines. The synthesis

Conjugated nitrosoalkenes as Michael acceptors in carbon–carbon bond forming reactions: a review and perspective

• Yaroslav D. Boyko,
• Valentin S. Dorokhov,
• Alexey Yu. Sukhorukov and
• Sema L. Ioffe

Beilstein J. Org. Chem. 2017, 13, 2214–2234, doi:10.3762/bjoc.13.220

• ). It is believed that the initially formed α-cyanooximes 85 undergo rapid cyclization to isoxazole derivatives 86. Interestingly, in the case of a more sterically hindered 3-chloronorcamphor oxime, the corresponding α-cyanooxime 85a was obtained, which did not undergo cyclization to isoxazole

Isoxazole derivatives as new nitric oxide elicitors in plants

• Anca Oancea,
• Emilian Georgescu,
• Florentina Georgescu,
• Alina Nicolescu,
• Elena Iulia Oprita,
• Catalina Tudora,
• Lucian Vladulescu,
• Marius-Constantin Vladulescu,
• Florin Oancea and
• Calin Deleanu

Beilstein J. Org. Chem. 2017, 13, 659–664, doi:10.3762/bjoc.13.65

• ], antinociceptive [12] and anticancer [13] activities. Several isoxazole derivatives have GABAA antagonist [14] and T-type Ca2+ channel blocking activities [15]. Commercial drugs featuring an isoxazole moiety include the COX-2 inhibitor Valdecoxib and the β-lactam antibiotics Cloxacillin and Dicloxacillin. An

• orchestration of various plant physiological responses, playing an important role in the regulation of interactions between plant and microorganisms and in plant defense mechanisms against stresses [18][19]. Consequently, there is interest in the biological evaluation of further isoxazole derivatives. Many

• procedures towards isoxazole derivatives were developed [36][37]. As part of our continued efforts to develop simple synthetic routes towards bioactive heterocyclic compounds [38][39][40][41][42][43], we report here the synthesis of several 3,5-isoxazole derivatives, bearing benzo[1,3]dioxole and thiophene

Synthesis of 2,1-benzisoxazole-3(1H)-ones by base-mediated photochemical N–O bond-forming cyclization of 2-azidobenzoic acids

• Daria Yu. Dzhons and
• Andrei V. Budruev

Beilstein J. Org. Chem. 2016, 12, 874–881, doi:10.3762/bjoc.12.86

• -azidobenzoate anion photolysis that results in the heterocyclization product. Selected examples of biologically active, fused 2,1-isoxazole derivatives. Photochemical cyclization of substituted 2-azidobenzoic acids and possible reaction mechanism [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49

Development of variously functionalized nitrile oxides

• Haruyasu Asahara,
• Keita Arikiyo and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2015, 11, 1241–1245, doi:10.3762/bjoc.11.138

• -functionalized isoxazole derivatives. Since the amide was prepared by the cycloaddition reaction of ethynylbenzene and N-methylcarbamoylnitrile oxide, the nitrile oxide served as the equivalent of the nitrile oxides bearing a variety of functional groups such as carboxy, alkoxycarbonyl, carbamoyl, acyl 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

• isoxazolium N-ylides from N-unsubstituted isoxazole derivatives. The formation of such ylides as reactive intermediates in the reactions of bases on isoxazolium salts was earlier supposed [6][7][8][9]. However, the detection of isoxazolium N-ylides has never been reported. Recently, we found an alternative

A new fluorescent chemosensor for fluoride anion based on a pyrrole–isoxazole derivative

• Zhipei Yang,
• Kai Zhang,
• Fangbin Gong,
• Shayu Li,
• Jun Chen,
• Jin Shi Ma,
• Lyubov N. Sobenina,
• Albina I. Mikhaleva,
• Guoqiang Yang and
• Boris A. Trofimov

Beilstein J. Org. Chem. 2011, 7, 46–52, doi:10.3762/bjoc.7.8

• compounds, and are used as antimicrobial antifungal and herbicide agents [10][11]. Research on the mechanism of anion recognition is helpful for understanding the biological activities of pyrrole–isoxazole derivatives. From UV–vis and fluorescence titration experiments it was found that the receptor 1 could

Addition of lithiated enol ethers to nitrones and subsequent Lewis acid induced cyclizations to enantiopure 3,6-dihydro-2H-pyrans – an approach to carbohydrate mimetics

• Fabian Pfrengle and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2010, 6, No. 75, doi:10.3762/bjoc.6.75

• further diversification of our pyran derivatives, e.g., by 1,3-dipolar cycloaddition leading to isoxazole derivatives [22] or, by addition of nucleophiles to this electrophilic unit [9]. Compounds 8 and 21 proved to be excellent precursors for the stereoselective preparation of enantiopure aminopyrans

A surprising new route to 4-nitro-3-phenylisoxazole

• Henning Hopf,
• Aboul-fetouh E. Mourad and
• Peter G. Jones

Beilstein J. Org. Chem. 2010, 6, No. 68, doi:10.3762/bjoc.6.68

• obtained in 40% yield. Keywords: cinnamyl alcohol; furoxan derivatives; isoxazole derivatives; X-ray diffraction; Introduction The isoxazole ring system, which can be easily obtained by [3 + 2] cycloaddition of nitric oxides to alkynes, is of interest since it forms a part of various biodynamic agents

• . Isoxazole derivatives that act as antithrombotic, hypolipidemic, nootropic, antiviral, antiobesity, and CNS modulation agents have been described [1]. On the other hand, derivatives having liquid crystalline properties have received a great deal of attention as they have a wide variety of applications