Trifluoromethylated hydrazones and acylhydrazones as potent nitrogen-containing fluorinated building blocks

• Zhang Dongxu

Beilstein J. Org. Chem. 2023, 19, 1741–1754, doi:10.3762/bjoc.19.127

• -withdrawing property of the trifluoromethyl group is key to this coupling reaction [45] (Scheme 7). Trifluoromethylated hydrazonoyl halides Hydrazonoyl halides, which offer a reactive 1,3-dipole, can easily be transformed to nitrile imines in the presence of a base, and they have shown to be useful building

• , 1,4-naphthoquinones, o-trimethylsilylphenyl triflate and chalcones have all been reacted with fluorinated nitrile imines to give a series of fluoroalkylated pyrazoles by Jasiński’s team [67][68][69][70][71][72] (Scheme 11a). Subsequently, Hu et al., Nie et al., and Ma et al. have all independently

• as fluorinated building blocks for the synthesis of difluoromethylated pyrazole derivatives by such [3 + 2] cycloaddition reactions [73][84][85] (Scheme 13). These studies therefore emphasize that fluoromethylated nitrile imines are versatile building blocks for [3 + 2] and [3 + 3] cycloaddition

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

• -8057 Zurich, Switzerland Department of Physical Chemistry, Faculty of Chemistry, University of Lodz, Pomorska 163/165, 90236 Łódź, Poland 10.3762/bjoc.17.108 Abstract In-situ-generated N-aryl nitrile imines derived from trifluoroacetonitrile efficiently react with polycyclic 1,4-quinones, yielding

• naphthoquinone-derived products and low-intensity bands in the visible region (≈400 nm) for the anthraquinone series. Keywords: [3 + 2]-cycloadditions; fluorinated compounds; fused pyrazoles; N-heterocycles; nitrile imines; 1,4-quinones; Introduction The 1,4-quinone scaffold belongs to the most important

• exclusively [16]. Noteworthy, [3 + 2]-cycloadditions of nitrile imines to the C=O group of 1,4-quinones have not yet been reported. In a historical work by Rolf Huisgen et al., the first [3 + 2]-cycloadditions of some 1,4-quinones, e.g., 1,4-naphthoquinone (1a), with C,N-diphenyl nitrile imine (2) were

3-Pyridylnitrene, 2- and 4-pyrimidinylcarbenes, 3-quinolylnitrenes, and 4-quinazolinylcarbenes. Interconversion, ring expansion to diazacycloheptatetraenes, ring opening to nitrile ylides, and ring contraction to cyanopyrroles and cyanoindoles

• Curt Wentrup,
• Nguyen Mong Lan,
• Adelheid Lukosch,
• Pawel Bednarek and
• David Kvaskoff

Beilstein J. Org. Chem. 2013, 9, 743–753, doi:10.3762/bjoc.9.84

• to the formation of glutacononitriles in low yields [12]. In contrast, 3-pyridylnitrene (10) undergoes a different type of ring opening to the observable nitrile ylide 11 and subsequently the ketenimine 12 (Scheme 3) [13]. Nitrile imines [14] and nitrile ylides [15][16] may have either allenic or

Photochemical and thermal intramolecular 1,3-dipolar cycloaddition reactions of new o-stilbene-methylene-3-sydnones and their synthesis

• Kristina Butković,
• Željko Marinić,
• Krešimir Molčanov,
• Biserka Kojić-Prodić and
• Marija Šindler-Kulyk

Beilstein J. Org. Chem. 2011, 7, 1663–1670, doi:10.3762/bjoc.7.196

• % yield). Keywords: [3 + 2] cycloaddition; isoindoles; nitrile imines; pyrazoles; sydnones; Introduction Sydnones belong to the group of five-membered heterocyclic compounds referred to as being "mesoionic" and have been widely studied since their discovery [1][2][3][4][5]. They can be represented as