Germanyl triazoles as a platform for CuAAC diversification and chemoselective orthogonal cross-coupling

• John M. Halford-McGuff,
• Thomas M. Richardson,
• Aidan P. McKay,
• Frederik Peschke,
• Glenn A. Burley and
• Allan J. B. Watson

Beilstein J. Org. Chem. 2024, 20, 3198–3204, doi:10.3762/bjoc.20.265

• reactivity compared to other alkynes, which typically require much shorter reaction times. Extending the reaction time provided a higher conversion to the product 14. Yields were observed to be greater for aryl azides (e.g., 4 vs 6). Heterocycles such as pyridine (1), pyrimidine (10), phenothiazine (11), and

Morpholine-mediated defluorinative cycloaddition of gem-difluoroalkenes and organic azides

• Tzu-Yu Huang,
• Mario Djugovski,
• Sweta Adhikari,
• Destinee L. Manning and
• Sudeshna Roy

Beilstein J. Org. Chem. 2023, 19, 1545–1554, doi:10.3762/bjoc.19.111

• and benzyl azides was examined. An array of para- and meta-substituted aryl azides was amenable to the optimized conditions. The presence of electron-withdrawing groups worked well affording the products with m-cyano (4a), 3,5-dimethoxy (4b), m-fluoro (4c), and p-chloro (4d) substitution in 39–58

• product 4f containing a 3,4,5-trimethoxyphenyl substituent was afforded in a moderate 36% yield. Electron-donating groups on the aryl azide, such as biphenyl at the para-position gave product 4g in 31% yield. A clear trend was observed: electron-withdrawing groups on the aryl azides facilitated the

Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives

• Yi Liu,
• Puying Luo,
• Yang Fu,
• Tianxin Hao,
• Xuan Liu,
• Qiuping Ding and
• Yiyuan Peng

Beilstein J. Org. Chem. 2021, 17, 2462–2476, doi:10.3762/bjoc.17.163

• trace amount of the desired product was observed. Control experiments indicated that the possible reaction mechanism may proceed through a Cu(II)/Rh(III)-promoted radical process. Aryl azides are versatile intermediates, which were widely used in synthetic and medicinal chemistry as well as material and

A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

• Pezhman Shiri,
• Ali Mohammad Amani and
• Thomas Mayer-Gall

Beilstein J. Org. Chem. 2021, 17, 1600–1628, doi:10.3762/bjoc.17.114

• subsequent elimination of HBr leads to the triazole ring [39]. Another metal-free strategy to 1,4,5-trisubstituted 1,2,3-triazoles 8 was realized by regioselective reaction of aryl azides 7 with enaminones 6 in the presence of triethylamine, water, and ionic liquid (IL). This method exhibits good functional

• ) [45]. In 2020, Ramachary et al. reported the 1,3-dipolar cycloaddition of various enones 43 and 46 with less reactive vinyl/alkyl/aryl azides 44 via an enolate-mediated organocatalyst. This protocol provides diverse double C- and N-vinylated 1,2,3-triazole derivatives and C-vinylated 1,2,3-triazole

• -substituted cyclic enones treated successfully with azidophiles to give good yield of the corresponding double C- and N-vinylated 1,2,3-triazole derivatives 45. Then, the reaction was extended to some aryl and alkyl azides and different cyclic enones. Moreover, a variety of vinyl, alkyl, and aryl azides were

Assembly of fully substituted triazolochromenes via a novel multicomponent reaction or mechanochemical synthesis

• Robby Vroemans,
• Yenthel Verhaegen,
• My Tran Thi Dieu and
• Wim Dehaen

Beilstein J. Org. Chem. 2018, 14, 2689–2697, doi:10.3762/bjoc.14.246

• % yield (Scheme 3). Finally, the scope with respect to organic azides was investigated by performing reactions with alkyl and aryl azides 4a–g. Electron-rich aliphatic azides produced products 5j–l in moderate yields. Additionally, electron-rich and electron-deficient aromatic azides were explored

Diazirine-functionalized mannosides for photoaffinity labeling: trouble with FimH

• Femke Beiroth,
• Tomas Koudelka,
• Thorsten Overath,
• Stefan D. Knight,
• Andreas Tholey and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2018, 14, 1890–1900, doi:10.3762/bjoc.14.163

• ) and irradiation of the ligand–protein complex to form an excited intermediate, which eventually leads to a covalently crosslinked ligand–receptor conjugate, which has to be identified by mass spectrometry (Figure 1). Three widely used photoreactive groups are aryl azides, benzophenones and diazirines

Solvent-free copper-catalyzed click chemistry for the synthesis of N-heterocyclic hybrids based on quinoline and 1,2,3-triazole

• Martina Tireli,
• Silvija Maračić,
• Stipe Lukin,
• Marina Juribašić Kulcsár,
• Dijana Žilić,
• Mario Cetina,
• Ivan Halasz,
• Silvana Raić-Malić and
• Krunoslav Užarević

Beilstein J. Org. Chem. 2017, 13, 2352–2363, doi:10.3762/bjoc.13.232

• S15–S19 in Supporting Information File 1. Raman spectra of all studied compounds, the alkyne 4 and the isolated products 5–8, are characterized by strong bands assigned to various vibrations of aromatic rings (Figure 1 and Supporting Information File 1, Table S1). Dried aryl azides were excluded from

• corresponding aryl azides (0.5 M in tert-butyl methyl ether, ≥95.0%) that were obtained commercially from Sigma-Aldrich. To ensure solvent-free milling conditions, tert-butyl methyl ether was evaporated under vacuo immediatelly before the milling was commenced. The progress of reactions was monitored using thin

Ultrasound-promoted organocatalytic enamine–azide [3 + 2] cycloaddition reactions for the synthesis of ((arylselanyl)phenyl-1H-1,2,3-triazol-4-yl)ketones

• Gabriel P. Costa,
• Natália Seus,
• Juliano A. Roehrs,
• Raquel G. Jacob,
• Ricardo F. Schumacher,
• Thiago Barcellos,
• Rafael Luque and
• Diego Alves

Beilstein J. Org. Chem. 2017, 13, 694–702, doi:10.3762/bjoc.13.68

• -amides with a range of substituted aryl azides providing and efficient access to new N-aryl-1,2,3-triazoyl carboxamides in good to excellent yields and short reaction times of [75]. However, to the best of our knowledge, the use of sonochemistry to synthesize complex selenium-functionalized 1,2,3

Catalytic Wittig and aza-Wittig reactions

• Zhiqi Lao and
• Patrick H. Toy

Beilstein J. Org. Chem. 2016, 12, 2577–2587, doi:10.3762/bjoc.12.253

• addition to phosphine oxide-catalyzed aza-Wittig reactions, Ding’s research group has also explored the use of phosphine catalysis in such reactions. In their initial report regarding this strategy, they used 1 to catalyze intramolecular reactions that converted aryl azides 68 into 4(3H)-quinazolinones 69

Copper-catalyzed [3 + 2] cycloaddition of (phenylethynyl)di-p-tolylstibane with organic azides

• Mizuki Yamada,
• Mio Matsumura,
• Yuki Uchida,
• Masatoshi Kawahata,
• Yuki Murata,
• Naoki Kakusawa,
• Kentaro Yamaguchi and
• Shuji Yasuike

Beilstein J. Org. Chem. 2016, 12, 1309–1313, doi:10.3762/bjoc.12.123

• yields. The CuAAC reaction of 1 with aryl azides such as 4-methylphenyl and 4-cyanophenyl azide gave a complex mixture, presumably due to the steric hindrance introduced by the aryl groups. The regiochemistry of 5-stibanotriazole 3a was elucidated by 1H NMR and confirmed by single-crystal X-ray analysis

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

• 2,1-benzisoxazole-3(1H)-ones is reported. The optimization and scope of this cyclization reaction is discussed. It is shown that an essential step of the ring closure of 2-azidobenzoic acids is the formation and photolysis of 2-azidobenzoate anions. Keywords: aryl azides; azepinones; 2,1

• nitro compounds [17][18][19][20][21], two other routes are available: the annulation of nitroso compounds [22][23] and the thermal [24], catalytic [25][26][27] or photochemical cyclization of aryl azides [28][29][30][31]. However, the presence of electron-withdrawing substituents in the 3-, 5- and 7

• pericyclic mechanism for the formation of heterocyclic compounds in the pyrolysis of aryl azides with unsaturated ortho-substituents. A possible reaction mechanism for the photochemical formation of 2 (Scheme 1, path: 1 → A → 2) based on the report by Platz et al. [54] includes the benzofuroxan formation by

Synthesis of chiral N-phosphoryl aziridines through enantioselective aziridination of alkenes with phosphoryl azide via Co(II)-based metalloradical catalysis

• Jingran Tao,
• Li-Mei Jin and
• X. Peter Zhang

Beilstein J. Org. Chem. 2014, 10, 1282–1289, doi:10.3762/bjoc.10.129

• aryl azides have been effectively employed for metal-catalyzed asymmetric aziridination [16][17][18][19], the catalytic system based on other types of azides, such as phosphoryl azides, remains underdeveloped. Phosphoryl azides, a family of common organic azides that can be directly synthesized from

• different types of nitrene sources, particularly with sulfonyl and aryl azides [16][18]. Computational and experimental studies have provided increasing evidences to suggest a stepwise radical mechanism for the Co(II)-catalyzed metalloradical aziridination that involves an unprecedented Co(III)–nitrene

• (Table 1, entry 7). Further improvement in enantioselectivity was achieved when [Co(P4)] (P4 = 3,5-DitBu-Xu(2’-Naph)Phyrin), a second-generation MRC catalyst that was previously shown to be optimal for asymmetric olefin aziridination with aryl azides [18], was used as a catalyst, reaching 65% ee but in a

[3 + 2]-Cycloadditions of nitrile ylides after photoactivation of vinyl azides under flow conditions

• Stephan Cludius-Brandt,
• Lukas Kupracz and
• Andreas Kirschning

Beilstein J. Org. Chem. 2013, 9, 1745–1750, doi:10.3762/bjoc.9.201

• refer to [6][7][8][9][10][11][12][13][14][15]. Recently, the Seeberger group has published a flow protocol on the photochemical degradation of aryl azides and the subsequent formation of 3H-azepinones [16]. With the emergence of continuous processes involving miniaturized flow reactors in organic

Flow photochemistry: Old light through new windows

• Jonathan P. Knowles,
• Luke D. Elliott and
• Kevin I. Booker-Milburn

Beilstein J. Org. Chem. 2012, 8, 2025–2052, doi:10.3762/bjoc.8.229

Continuous flow photolysis of aryl azides: Preparation of 3H-azepinones

• Farhan R. Bou-Hamdan,
• François Lévesque,
• Alexander G. O'Brien and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2011, 7, 1124–1129, doi:10.3762/bjoc.7.129

• Berlin, Germany 10.3762/bjoc.7.129 Abstract Photolysis of aryl azides to give nitrenes, and their subsequent rearrangement in the presence of water to give 3H-azepinones, is performed in continuous flow in a photoreactor constructed of fluorinated ethylene polymer (FEP) tubing. Fine tuning of the

• ]. Overall, aryl azides, which are simple to prepare from the corresponding aniline derivative, are convenient precursors for the synthesis of azepine derivatives. However, the utility of the process is offset by the long reaction times required and by the low yields arising from poor selectivity and

• column chromatography. Rearrangements of aryl azides bearing electron withdrawing substituents are better represented in the literature than their electron donating congeners [31], and this was reflected in our compound selection. Methyl 2-azidobenzoate (8b), the corresponding acid 8c and dimethyl 2

En route to photoaffinity labeling of the bacterial lectin FimH

• Thisbe K. Lindhorst,
• Michaela Märten,
• Andreas Fuchs and
• Stefan D. Knight

Beilstein J. Org. Chem. 2010, 6, 810–822, doi:10.3762/bjoc.6.91

• photoaffinity-labeling of FimH. Our earlier work suggested that diazirines are more useful photoactive groups than aryl azides and benzophenones [15]. Therefore, the synthesis of a biotin-labeled daizirine-functionalized mannoside was our next target. In this synthesis, aspartic acid was utilized as the

EPR and pulsed ENDOR study of intermediates from reactions of aromatic azides with group 13 metal trichlorides

• Giorgio Bencivenni,
• Riccardo Cesari,
• Daniele Nanni,
• Hassane El Mkami and
• John C. Walton

Beilstein J. Org. Chem. 2010, 6, 713–725, doi:10.3762/bjoc.6.84

• Schäfer et al. [46], was also employed for some computations. General procedure for the reaction of aryl azides with indium trichloride. The starting azide (1 mmol) was added at 0 °C to an acetonitrile solution of indium trichloride (1.1 mmol) in DCM (4 mL) and stirred for 5 min at 0 °C. Gas was evolved

• samples were photolysed with a 500 W super pressure Hg arc. General procedure for the reaction of aryl azides with dichloroindium hydride. The starting azide (1 mmol) was added at 0 °C to an acetonitrile solution of dichloroindium hydride (1.1 mmol), generated in situ by stirring under an argon atmosphere

• corresponding aromatic amine was identified by comparison with literature data. General procedure for the reaction of aryl azides with AlCl3. Aluminium trichloride (1.1 mmol) was dried under reduced pressure at 25 °C for 1 h. Then DCM (3 mL) was added and a DCM solution of the azide (1 mmol in 1 mL) was