Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

• -thiofuranoside 141 was prepared from methyl 2,3-anhydro-α-D-ribofuranoside (133a), which was first reacted with sodium azide followed by the similar synthetic route as described above, affording 3,5-anhydro-2-azido-3-thiofuranoside 139. The azido derivative 139 generated the final product 2-amino-3,5-anhydro-3

• chloromethylthiirane (epithiochlorohydrin, 398a), with hard and weak nucleophiles [105][106][107][108][109], including phenoxides [105], carboxylates and dicarboxylates [106][107], potassium cyanide, sodium azide, hydroxylamine, trifluoromethanesulfonamide, and pyridine [108]. However, the method could only applied to

Oxime radicals: generation, properties and application in organic synthesis

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Alexander S. Budnikov and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107

• -unsaturated oxime an unusual six-membered oxazine 133h was reported as the major product [133]. A similar cyclization of oximes 134 with the introduction of an azido group was carried out using TMSN3 as an azide source (Scheme 45) [134]. The reaction is applicable for β,γ-unsaturated oximes having both aryl

Synthesis of new asparagine-based glycopeptides for future scanning tunneling microscopy investigations

• Laura Sršan and
• Thomas Ziegler

Beilstein J. Org. Chem. 2020, 16, 888–894, doi:10.3762/bjoc.16.80

• the anticipated glycopeptides, we started from the respective fully acetylated β-ᴅ-glycosyl azides 1a–f in the gluco, galacto, manno, cello, lacto, and malto series (Scheme 1). These glycosyl azides were prepared from the corresponding halogenoses by the treatment with 1.2 equivalents of sodium azide

• NaN3 in DMF) [23], the azide 1c could be obtained in 33% yield (compared to the reported 13%). Attempts to prepare the corresponding α-ᴅ-mannosyl azide under various previously described conditions [27][28] failed in our hands though. Next, the glycosyl azides 1a–f were converted into the corresponding

Preparation and in situ use of unstable N-alkyl α-diazo-γ-butyrolactams in Rh^II-catalyzed X–H insertion reactions

• Maria Eremeyeva,
• Daniil Zhukovsky,
• Dmitry Dar’in and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2020, 16, 607–610, doi:10.3762/bjoc.16.55

• -ethoxalyl-γ-lactams 6a–c, prepared by oxalylation of the respective γ-lactams as decribed previously [1], underwent a rapid diazo transfer reaction via the conventional protocol [4][5] employing 4-nitrobenzenesulfonyl azide and DBU. A quick filtration through a plug of alumina (in lieu of silica gel, which

Regioselectively α- and β-alkynylated BODIPY dyes via gold(I)-catalyzed direct C–H functionalization and their photophysical properties

• Takahide Shimada,
• Shigeki Mori,
• Masatoshi Ishida and
• Hiroyuki Furuta

Beilstein J. Org. Chem. 2020, 16, 587–595, doi:10.3762/bjoc.16.53

• -tethered BODIPY derivatives serve as a substrate in the copper-catalyzed azide–alkyne cycloaddition (CuAAC) reaction, which is known as “click” reaction, allowing for a biological tissue labelling [35][36]. In addition, ethynyl-substituted BODIPYs yield unique π-conjugated BODIPY-based macrocycles by

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

• employed procedures for the creation of triazole products is the Huisgen azide–alkyne cycloaddition, and the reaction selectively forms one type of triazole products. Many of the alkyne and azide substrates are commercially available, many others can easily be prepared with a good range of functional

• groups. The intramolecular reaction of an alkyne as a dipolarophile with an azide as a 1,3-dipole to produce the desired 1,2,3-triazole motif is a model of “click” chemistry. The concept of “click” chemistry is an idiom that was developed by Sharpless and Meldal and later by others to describe organic

• definition and fails as a real “click” reaction. Although this cyclization reaction requires elevated temperatures and often yields both the 1,4- and 1,5-regioisomers, the Cu or Ru alkyne–azide cycloaddition falls exactly into the above definition [11]. In this respect, the copper-catalyzed cycloaddition

KOt-Bu-promoted selective ring-opening N-alkylation of 2-oxazolines to access 2-aminoethyl acetates and N-substituted thiazolidinones

• Qiao Lin,
• Shiling Zhang and
• Bin Li

Beilstein J. Org. Chem. 2020, 16, 492–501, doi:10.3762/bjoc.16.44

• TMSN3 as the azide source [10] (Scheme 1a). Coates described a Co2(CO)8-catalyzed ring-opening hydroformylation of oxazolines for the synthesis of β-amidoaldehydes [11] (Scheme 1a). However, the ring-opening N-alkylation of 2-oxazolines to produce 2-aminoethyl acetate derivatives under basic conditions

Aerobic synthesis of N-sulfonylamidines mediated by N-heterocyclic carbene copper(I) catalysts

• Faïma Lazreg,
• Marie Vasseur,
• Alexandra M. Z. Slawin and
• Catherine S. J. Cazin

Beilstein J. Org. Chem. 2020, 16, 482–491, doi:10.3762/bjoc.16.43

• between alkyne, sulfonyl azide and amine/alcohol was described as a synthetic route to generate sulfonyltriazole intermediates. However, the presence of additives and high catalyst loading (CuI 10 mol %) were required for the synthesis of N-sulfonylimidates (Scheme 1, left). Over the last two decades

• deprotonates the triazolium salt (Scheme 2). The reactivity of a series of cationic copper(I) complexes (1–6) was evaluated at 0.5 mol % loading using tosyl azide, phenylacetylene and diisopropylamine as benchmark substrates [31][32]. Various solvents were evaluated at room temperature under aerobic conditions

• conversion with respectively 96% (10a), 95% (10c) and 93% (10g) isolated yields, in reaction times of 3 to 4.5 hours. Regarding the 2,4,6-triisopropylsulfonyl azide, a slight decrease in the reactivity was observed (66%, 10f), presumably due to the steric hindrance of the substrate. Electron-withdrawing

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

• Mingbing Zhong,
• Xavier Pannecoucke,
• Philippe Jubault and
• Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

• loss of a DAP ligand. Then, the [Cu(II)] complex reacts with TMSN3 to form a [Cu(II)]–N3 species that gives an azide radical through a homolytic dissociation induced by light irradiation. The formed azide radical reacts with the styrene to form a benzylic radical that is then oxidized by O2. The

• vinyl azide sensitization to allow the formation of the corresponding 2,5-disubstituted pyrrole (Scheme 34) [39]. The reaction was promoted by a visible-light irradiation (450 nm) using the complex [Cu(I)(dmp)(BINAP)]BF4, and the desired pyrrole was obtained in quantitative yield. Conclusion Over the

• lactone synthesis using a copper-photocatalyzed PCET reaction. Photocatalytic Pinacol coupling reaction catalyzed by [Cu(I)(pypzs)(BINAP)]BF4. The ligands of the copper complex are omitted for clarity. Azide photosensitization using a Cu-based photocatalyst. Funding This work was partially supported by

Photophysics and photochemistry of NIR absorbers derived from cyanines: key to new technologies based on chemistry 4.0

• Bernd Strehmel,
• Christian Schmitz,
• Ceren Kütahya,
• Yulian Pang,
• Anke Drewitz and
• Heinz Mustroph

Beilstein J. Org. Chem. 2020, 16, 415–444, doi:10.3762/bjoc.16.40

Architecture and synthesis of P,N-heterocyclic phosphine ligands

• Wisdom A. Munzeiwa,
• Bernard Omondi and
• Vincent O. Nyamori

Beilstein J. Org. Chem. 2020, 16, 362–383, doi:10.3762/bjoc.16.35

• alkyne–azide cycloaddition reaction has been applied successfully to prepare click-phosphine ligands [72]. The presence of three nitrogen atoms within the five-membered ring results in a high activation of the α-position and the highly acidic nature of the proton makes it easy for abstraction. Sharpless

• et al. [73] reported on the synthesis of 1,5-disubstituted triazoles and Liu et al. [74] used this procedure to synthesize triazolylphosphine ligands with the phosphorous substituent in the α-position (Scheme 12). For this, the aryl azide 64 was reacted with bromomagnesium acetylides 65 to generate

• reaction is catalyzed by a copper(I) complex of 2,6-bis(4R,5S)-4,5-diphenyl-4,5-dihydrooxazol-2-yl)pyridine. The triazole amine 119 is obtained in situ by the reaction with the corresponding azide, which is catalyzed by the catalyst from the prior step. Finally, lithiation of compound 119 and addition of

Combination of multicomponent KA² and Pauson–Khand reactions: short synthesis of spirocyclic pyrrolocyclopentenones

• Riccardo Innocenti,
• Elena Lenci,
• Gloria Menchi and
• Andrea Trabocchi

Beilstein J. Org. Chem. 2020, 16, 200–211, doi:10.3762/bjoc.16.23

• imposed by the adjacent phenyl and cyclohexyl rings [59]. The treatment of compound 5 under Schmidt reaction conditions with sodium azide in TFA [60] resulted in the conversion to the corresponding six-membered ring lactam 39 in 41% yield, demonstrating the reactivity of the enone 5 at the carbonyl group

Halogen-bonding-induced diverse aggregation of 4,5-diiodo-1,2,3-triazolium salts with different anions

• Xingyu Xu,
• Shiqing Huang,
• Zengyu Zhang,
• Lei Cao and
• Xiaoyu Yan

Beilstein J. Org. Chem. 2020, 16, 78–87, doi:10.3762/bjoc.16.10

• candidates for XB donors, which is mainly due to the ease of preparation via a copper-catalyzed click reaction between azide and alkyne [38][39]. 1,2,3-Triazoles and 1,2,3-triazolium-based XB activators have been found applications in catalytic reactions [40][41] and anion recognition [42]. Recently, we

Synthesis of C-glycosyl phosphonate derivatives of 4-amino-4-deoxy-α-ʟ-arabinose

• Lukáš Kerner and
• Paul Kosma

Beilstein J. Org. Chem. 2020, 16, 9–14, doi:10.3762/bjoc.16.2

• and azide-to-amine conversion, compound 17 was isolated as the 4-amino-4-deoxy-ʟ-ribopyranosyl derivative. The configuration was determined from the NMR data. Position H-2 at 4.02 ppm appeared as a broad doublet with small homonuclear coupling constants, as would be expected for a manno spin system

SnCl₄-catalyzed solvent-free acetolysis of 2,7-anhydrosialic acid derivatives

• Kesatebrhan Haile Asressu and
• Cheng-Chung Wang

Beilstein J. Org. Chem. 2019, 15, 2990–2999, doi:10.3762/bjoc.15.295

• characterize the formation of the 2,7-anhydro skeleton, triols 2 and 3 were treated with 2,2-dimethoxypropane in the presence of a catalytic amount of camphorsulfonic acid (CSA) in acetonitrile to afford compound 4 in 63% and azide acceptor 4a in quantitative yield (Scheme 1). The crystal structure of 4

Influence of the cis/trans configuration on the supramolecular aggregation of aryltriazoles

• Sara Tejera,
• Giada Caniglia,
• Rosa L. Dorta,
• Andrea Favero,
• Javier González-Platas and
• Jesús T. Vázquez

Beilstein J. Org. Chem. 2019, 15, 2881–2888, doi:10.3762/bjoc.15.282

• ) The triflyl azide was prepared as follows: Sodium azide (922 mg, 14.2 mmol), dissolved in pyridine (15 mL), was cooled to 0 °C under vigorous stirring. Then, triflic anhydride (1.7 mL, 10.1 mmol) was added dropwise, and the reaction mixture was left for 2 h at 0 °C under vigorous stirring. During that

• cooled in an ice bath and the above-prepared solution of triflyl azide added dropwise. The resulting green reaction mixture was allowed to warm to room temperature and left for 20 h. The reaction mixture was diluted with CH2Cl2 (100 mL) and extracted using diluted HCl until the pH value was acidic (4

Diversity-oriented synthesis of spirothiazolidinediones and their biological evaluation

• Sambasivarao Kotha,
• Gaddamedi Sreevani,
• Lilya U. Dzhemileva,
• Milyausha M. Yunusbaeva,
• Usein M. Dzhemilev and
• Vladimir A. D’yakonov

Beilstein J. Org. Chem. 2019, 15, 2774–2781, doi:10.3762/bjoc.15.269

• various diseases. Hence, we also modified the N-propargyl alcohol derivative 21 to 1,2,3-triazolo alcohol derivative 24 by click chemistry using 4-nitrophenyl azide (23) and the corresponding triazolo alcohol derivative 24 was obtained as yellow solid in 80% yield (Scheme 9) [58]. All alcohol derivatives

Fluorinated maleimide-substituted porphyrins and chlorins: synthesis and characterization

• Valentina A. Ol’shevskaya,
• Elena G. Kononova and
• Andrei V. Zaitsev

Beilstein J. Org. Chem. 2019, 15, 2704–2709, doi:10.3762/bjoc.15.263

• . Complexes 2a and 2b readily reacted with the excess of NaN3 in DMF/DMSO to afford porphyrins 3a and 3b in high yields via the selective substitution of fluorine atoms in the para-position of the pentafluorophenyl substituents with four azide functions. The subsequent reduction of para-tetraazidoporphyrinato

• 1,2,3-triazole heterocycles via the copper-catalyzed azide–alkyne cycloaddition reaction (CuAAC) between alkynes and azides, developed independently by Sharpless [41] and Meldal [42]. In addition to the applications of triazoles as pharmacophores in the potential biologically active molecules, these

• ylide, generated in situ from sarcosine and paraformaldehyde. The reaction of chlorin 9 with the excess of NaN3 in DMF/DMSO resulted in tetraazide chlorin 10 in 85% yield after the purification. The reduction of azide groups in chlorin 10 with SnCl2 in MeOH gave tetraamino-substituted chlorin 11 which

Safe and highly efficient adaptation of potentially explosive azide chemistry involved in the synthesis of Tamiflu using continuous-flow technology

• Cloudius R. Sagandira and
• Paul Watts

Beilstein J. Org. Chem. 2019, 15, 2577–2589, doi:10.3762/bjoc.15.251

• , more than 60 synthetic routes have been developed to date, however, most of the synthetic routes utilise the potentially hazardous azide chemistry making them not green, thus not amenable to easy scale up. Consequently, this study exclusively demonstrated safe and efficient handling of potentially

• explosive azide chemistry involved in a proposed Tamiflu route by taking advantage of the continuous-flow technology. The azide intermediates were safely synthesised in full conversions and >89% isolated yields. Keywords: azide chemistry; continuous flow synthesis; hazardous; safe; Tamiflu; Introduction

• have been developed towards Tamiflu to date [1][2][3]. However, most of these synthetic approaches suffer from the use of potentially hazardous azide chemistry, thus raising safety concerns [4] and eventually ruled out for large scale synthesis in batch systems [1][2]. The importance and use of azide

A new approach to silicon rhodamines by Suzuki–Miyaura coupling – scope and limitations

• Thines Kanagasundaram,
• Antje Timmermann,
• Carsten S. Kramer and
• Klaus Kopka

Beilstein J. Org. Chem. 2019, 15, 2569–2576, doi:10.3762/bjoc.15.250

• resulting rhodamine 28c could be a possible substrate for the conversion into an azide and follow-up click reactions with alkyne-substituted tumor vectors. While heating of amine 28a to the corresponding boroxine 28b lead to formation of a brown solid (presumably due to degradation), the reaction of

Combining the Ugi-azide multicomponent reaction and rhodium(III)-catalyzed annulation for the synthesis of tetrazole-isoquinolone/pyridone hybrids

• Gerardo M. Ojeda,
• Prabhat Ranjan,
• Pavel Fedoseev,
• Lisandra Amable,
• Upendra K. Sharma,
• Daniel G. Rivera and
• Erik V. Van der Eycken

Beilstein J. Org. Chem. 2019, 15, 2447–2457, doi:10.3762/bjoc.15.237

• Natural Product Research, Faculty of Chemistry, University of Havana, Zapata y G, 10400, La Habana, Cuba Peoples´ Friendship University of Russia (RUDN University) Miklukho-Maklaya Street 6, 117198 Moscow, Russia 10.3762/bjoc.15.237 Abstract An efficient sequence based on the Ugi-azide reaction and

• rhodium catalyst to promote C(sp2)–H activation in the presence of a suitable directing group. The Ugi-azide reaction provides broad molecular diversity and enables the introduction of the tetrazole moiety, which may further assist the catalytic reaction by coordinating the metal center. The scope of the

• prospect of the tetrazole hybridization strategy in drug discovery. Among the most versatile methods for obtaining tetrazoles are the Ugi-azide four-component reaction (Ugi-azide-4CR) [14][15][16] and the 1,3-dipolar cycloaddition of azides with (acyl)cyanides [17][18]. The Ugi-azide-4CR enables the

In water multicomponent synthesis of low-molecular-mass 4,7-dihydrotetrazolo[1,5-a]pyrimidines

• Irina G. Tkachenko,
• Sergey A. Komykhov,
• Vladimir I. Musatov,
• Svitlana V. Shishkina,
• Viktoriya V. Dyakonenko,
• Vladimir N. Shvets,
• Mikhail V. Diachkov,
• Valentyn A. Chebanov and
• Sergey M. Desenko

Beilstein J. Org. Chem. 2019, 15, 2390–2397, doi:10.3762/bjoc.15.231

• several times [5][6]. A third approach (Scheme 1, reaction 3) is completely different and consists of the tetrazole ring formation through cyclization of dihydropyrimidinethiones with sodium azide [14]. Generally, all three approaches allow for the preparation of a broad range of compounds 3 with a wide

Click chemistry towards thermally reversible photochromic 4,5-bisthiazolyl-1,2,3-triazoles

• Chenxia Zhang,
• Kaori Morinaka,
• Mahmut Kose,
• Takashi Ubukata and
• Yasushi Yokoyama

Beilstein J. Org. Chem. 2019, 15, 2161–2169, doi:10.3762/bjoc.15.213

• , Zonguldak Bülent Ecevit University, 67100, Zonguldak, Turkey 10.3762/bjoc.15.213 Abstract Three new diarylethenes were synthesized from 1,2-bis(5-methyl-2-(4-substituted-phenyl)thiazol-4-yl)ethyne and benzyl azide through Ru(I)-catalyzed Huisgen cyclization reactions. The 4,5-bisthiazolyl-1,2,3-triazoles

• century, Sharpless and co-workers proposed the concept of “click chemistry” [14], which stands for the secure, quick, selective, general and facile reaction between two organic functional groups. In click chemistry, the Huisgen cyclization, which occurs between an organic azide and a terminal alkyne

• the organic azide we used commercially available benzyl azide. Since 1,2-bis(5-methyl-2-phenylthiazol-4-yl)ethyne was used in our previous research [32][33][34], we employed bisthiazolylethynes as the foundation for the skeleton of the target compounds. In order to examine the substituent effects of

1,2,3-Triazolium macrocycles in supramolecular chemistry

• Mastaneh Safarnejad Shad,
• Pulikkal Veettil Santhini and
• Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

• (iodine, bromine) and chalcogens (selenium and tellurium) [18]. While there are several strategies for the synthesis of triazoles, the Cu(II)-catalyzed azide–alkyne cycloaddition reaction (CuAAC click reaction) is considered as one of the most efficient, simple and mild approaches towards the preparation

• of 1,4-disubstituted 1,2,3- triazole units [19][20][21][22][23][24]. Macrocyclic ring closure can be achieved by the CuAAC of building blocks functionalized with both azide and alkyne, using [1 + 1], [2 + 2], [n + n] strategies depending on how much triazoles are needed to be included in the

Attempted synthesis of a meta-metalated calix[4]arene

• Christopher D. Jurisch and
• Gareth E. Arnott

Beilstein J. Org. Chem. 2019, 15, 1996–2002, doi:10.3762/bjoc.15.195

• yielding transformations to azide and 1,2,3-triazole derivatives which may have application in other areas of research. Keywords: calixarene; inherent chirality; mesoionic carbene; mononitration; ruthenacycle; Introduction Calix[4]arenes are a class of diverse macrocyclic compounds which have been the

• Ullmann-type coupling to give aryl azide 2, which readily reacted with phenylacetylene in a copper-catalyzed Huisgen 1,3-dipolar cycloaddition to give 1,2,3-triazole 3 (Scheme 1). The formation of the ruthenacycle was then achieved using Albrecht’s method involving regioselective methylation of triazole 3

• the solubility. An alternative route involving an azide-Sandmeyer reaction on monoaminocalix[4]arene was then envisaged, since the necessary monoaminocalix[4]arene would be accessible via a previously reported mononitration method [28][29][30][31]. However, this method for mononitration of