Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

• utility of their reaction, the authors studied the one-pot conversion of the vinyl azides to 2H-azirines 161. The carboazidation reaction for the aryl alkynes was completed in a comparable amount of time. A myriad of different functionalized π-systems was tolerated by the reaction, demonstrating its

Visible-light-mediated copper photocatalysis for organic syntheses

• Yajing Zhang,
• Qian Wang,
• Zongsheng Yan,
• Donglai Ma and
• Yuguang Zheng

Beilstein J. Org. Chem. 2021, 17, 2520–2542, doi:10.3762/bjoc.17.169

• [Cu(dap)2Cl] and visible light are necessary for this transformation. In 2013, Ollivier and co-workers [45] successfully applied the same strategy to the allylation of diphenyliodonium 2. In 2017, Liu’s group [46] reported the copper salt-catalyzed cyclization of vinyl azides 3 with ammonium

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

• products. The tolylvinyl azide substituted with methyl at the ortho position afforded a lower yield of the desired product. The vinyl azides containing 2-naphthyl, β-phenyl, and 1-((2-azidoallyl)oxy)-4-nitrobenzenevinyl azides formed the corresponding products in high yield as well. Moreover, the alkyl

• enone 46 reacted with aryl and vinyl azides to afford a moderate to high yield of the triazole products (Scheme 16) [46]. A simple one-pot two-stage strategy for the synthesis of disubstituted 4-chloro-, 4-bromo-, and 4-iodo-1,2,3-triazoles 50 from the reaction of the corresponding nonactivated alkynes

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

A sustainable strategy for the straightforward preparation of 2H-azirines and highly functionalized NH-aziridines from vinyl azides using a single solvent flow-batch approach

• Michael Andresini,
• Leonardo Degannaro and
• Renzo Luisi

Beilstein J. Org. Chem. 2021, 17, 203–209, doi:10.3762/bjoc.17.20

• preparation of 2H-azirines and their stereoselective transformation into highly functionalized NH-aziridines, starting from vinyl azides and organolithium compounds. The protocol has been developed using cyclopentyl methyl ether (CPME) as an environmentally benign solvent, resulting into a sustainable, safe

• of vinyl azides, or by other strategies involving oximes, imines and oxazoles [24]. One appealing strategy for the preparation of 2H-azirines involves the use of readily available vinyl azides [25][26][27][28][29][30]. However, the batch cyclization of vinyl azides into the corresponding 2H-azirines

• resulted in safer procedures for the preparation of 2H-azirines, offering valuable alternatives for production purposes. In 2013, Kirschning harnessed the photoinduced electrocyclization of vinyl azides in a microfluidic photoreactor yielding 2H-azirines as precursors of 1,3-dipolarophiles (Scheme 1a) [27

Photocatalyzed syntheses of phenanthrenes and their aza-analogues. A review

• Alessandra Del Tito,
• Havall Othman Abdulla,
• Davide Ravelli,
• Stefano Protti and
• Maurizio Fagnoni

Beilstein J. Org. Chem. 2020, 16, 1476–1488, doi:10.3762/bjoc.16.123

• sulfonyl radical, prone to start a tandem sulfonylation/annulation of vinyl azides [84]. Recently, the phenanthridine core was assembled through a radical cascade triggered by the trifluoromethylthiolation of N-(o-cyanobiaryl)acrylamides. The process occurred under visible-light irradiation (6 W blue LED

• heteroarylalkynes. Synthesis of noravicine (14.2a) and nornitidine (14.2b) alkaloids. Gram-scale synthesis of the alkaloid trisphaeridine (15.3). Synthesis of phenanthridines starting from vinyl azides. Synthesis of pyrido[4,3,2-gh]phenanthridines 17.5a–d through the radical trifluoromethylthiolation of N-(o

Oxidative radical ring-opening/cyclization of cyclopropane derivatives

• Yu Liu,
• Qiao-Lin Wang,
• Zan Chen,
• Cong-Shan Zhou,
• Bi-Quan Xiong,
• Pan-Liang Zhang,
• Chang-An Yang and
• Quan Zhou

Beilstein J. Org. Chem. 2019, 15, 256–278, doi:10.3762/bjoc.15.23

• and vinyl azides 92 for the synthesis of azaheterocyles 93 (Scheme 20) [98]. This strategy could also be applied to the synthesis of the quaternary indole alkaloid and melinonine-E. Quinones play an important role in organic chemistry because of their unique structure. In 2013, Malayappasamy and co

• cyclopropanols and vinyl azides. Ag(I)-catalyzed oxidative ring-opening of cyclopropanols with quinones. Ag(I)-catalyzed oxidative ring-opening of cyclopropanols with heteroarenes. Cu(I)-catalyzed oxidative ring-opening/trifluoromethylation of cyclopropanols. Cu(I)-catalyzed oxidative ring-opening and

Continuous multistep synthesis of 2-(azidomethyl)oxazoles

• Thaís A. Rossa,
• Nícolas S. Suveges,
• Marcus M. Sá,
• David Cantillo and
• C. Oliver Kappe

Beilstein J. Org. Chem. 2018, 14, 506–514, doi:10.3762/bjoc.14.36

• , Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil 22941-909, Research Center Pharmaceutical Engineering GmbH (RCPE), Inffeldgasse 13, 8010 Graz, Austria 10.3762/bjoc.14.36 Abstract An efficient three-step protocol was developed to produce 2-(azidomethyl)oxazoles from vinyl azides in a

• continuous-flow process. The general synthetic strategy involves a thermolysis of vinyl azides to generate azirines, which react with bromoacetyl bromide to provide 2-(bromomethyl)oxazoles. The latter compounds are versatile building blocks for nucleophilic displacement reactions as demonstrated by their

• integration; vinyl azides; Introduction Oxazoles are an important class of five-membered aromatic heterocycles containing one oxygen and one nitrogen atom in their structures. The oxazole moiety is relatively stable and is found widely in nature [1][2][3]. Naturally occurring oxazoles include compounds with

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• -methacryloylbenzamides is similar and includes alkyl substituents on the nitrogen atom and electron-rich and poor aromatic moieties. Mao and Zhou applied vinyl azides for the radical cross-coupling with sodium sulfinate salts (Scheme 56) [95]. They observed that the azide moiety decomposes during the reaction (loss of

• N2) which triggers an intramolecular cyclization reaction via a nitrogen-centred radical intermediate to form sulfonylated phenanthridines. The reaction is photocatalyzed by [Ru(bpy)3]Cl2 under irradiation with blue LEDs and proceeds smoothly for a variety of substituted vinyl azides and sulfonyl

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• using 18O2; no reaction occurred under N2 instead of O2; K2S2O8 rather than O2 served as initiator; the radical CF3SO2• could either extrude SO2 to CF3• or react with O2 to re-initiate the radical chain process (Scheme 7). Vinyl azides were used by Liu and co-workers as precursors of α

• -trifluoromethylated ketones by reaction of CF3SO2Na under photoredox catalysis. The substrate scope was broad and the reaction proceeded with high functional group tolerance; indeed, aryl-, alkyl-, hetero-functionalised terminal as well as non-terminal vinyl azides 15 were compatible with the reaction conditions. In

Reaction of allene esters with Selectfluor/TMSX (X = I, Br, Cl) and Selectfluor/NH₄SCN: Competing oxidative/electrophilic dihalogenation and nucleophilic/conjugate addition

• A. Srinivas Reddy and
• Kenneth K. Laali

Beilstein J. Org. Chem. 2015, 11, 1641–1648, doi:10.3762/bjoc.11.180

• presence of phosphane catalysts an umpolung addition takes place, whereby the nucleophilic addition occurs inversely at the beta-gamma double bond [22][23]. Vinyl azides have been prepared by hydroazidation of allenyl esters through a Michael-type addition with high regio- and stereoselectivity [24

[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

• Stephan Cludius-Brandt Lukas Kupracz Andreas Kirschning Institute of Organic Chemistry, Leibniz University Hannover, Schneiderberg 1b, 30167 Hannover, Germany 10.3762/bjoc.9.201 Abstract The photodenitrogenation of vinyl azides to 2H-azirines by using a photoflow reactor is reported and compared

• from the corresponding vinyl azide. Keywords: azirines; cycloaddition; flow chemistry; flow reactors; inductive heating; nitrile ylides; photochemistry; vinyl azides; Introduction Recently, photochemistry has seen a renaissance despite the fact that under batch conditions specialized reaction vessels

• photoinduced activation of vinyl azides 1, which gives rise to 2H-azirines 2 via vinyl nitrenes after the loss of molecular nitrogen and subsequent ring-opening under photochemical conditions to provide the nitrile ylides 3 (Scheme 1). For recent examples for the use of azirines in organic syntheses please

Multistep flow synthesis of vinyl azides and their use in the copper-catalyzed Huisgen-type cycloaddition under inductive-heating conditions

• Lukas Kupracz,
• Jan Hartwig,
• Jens Wegner,
• Sascha Ceylan and
• Andreas Kirschning

Beilstein J. Org. Chem. 2011, 7, 1441–1448, doi:10.3762/bjoc.7.168

• Lukas Kupracz Jan Hartwig Jens Wegner Sascha Ceylan Andreas Kirschning Institute of Organic Chemistry, Leibniz University Hannover, Schneiderberg 1b, 30167 Hannover, Germany 10.3762/bjoc.7.168 Abstract The multistep flow synthesis of vinyl azides and their application in the synthesis of

• vinyltriazoles is reported. The synthesis relies on a stable polymer-bound equivalent of iodine azide that serves to carry out 1,2-functionalization of alkenes in a telescope flow protocol. The intermediate 2-iodo azides are subjected to a DBU-mediated polymer-supported elimination step yielding vinyl azides in

• reactor. Keywords: flow reactor; inductive heating; iodine azide; polymer-supported reagents; vinyl azides; Introduction Azides are highly versatile organic functional groups and their preparation and their reactivity are well explored [1]. In contrast, the synthesis of vinyl azides is far away from