Azidophosphonium salt-directed chemoselective synthesis of (E)/(Z)-cinnamyl-1H-triazoles and regiospecific access to bromomethylcoumarins from Morita–Baylis–Hillman adducts

• Soundararajan Karthikeyan,
• Radha Krishnan Shobana,
• Kamarajapurathu Raju Subimol,
• J. Helen Ratna Monica and
• Ayyanoth Karthik Krishna Kumar

Beilstein J. Org. Chem. 2020, 16, 1579–1587, doi:10.3762/bjoc.16.130

• for the synthesis of 3-(bromomethyl)coumarins. Literature-reported cycloaddition reactions of MBH acetates involving azides and alkynes [24][25][26][27][28]. Synthetic methodologies for triazolations of MBH adducts. a) Literature-reported indirect triazolation of MBH adducts [32][33]. b) This work

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

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

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

• protecting groups [12]. Later, ruthenium complexes-catalyzed alkyne–azide cycloadditions (RuAACs) regioselectively produced the opposite form of the disubstituted triazoles. Thus, a wide range of azides was reacted with diverse nonactivated terminal alkyne substrates using ruthenium complexes to generate

• two-component or three-component “click” reactions. In the two-component reaction, acetylene compounds and organic azides were stirred in dimethylformamide or in a mixture of t-BuOH/H2O, 3:1, v/v as the solvent using diethylisopropylamine and SiO2–Cu. In the three-component example, acetylene species

• nitride-supported copper nanoparticles was disclosed by Islam and co-workers (Scheme 18) [79][80]. The nanocatalyst 87 was successfully used as a high-performance photoreactor promoting “click” reactions of alkynes with organic azides under light irradiation in the absence of basic condition. In the first

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

• area, reporting on the synthesis of the first heteroleptic bis-NHC and mixed NHC/phosphine copper(I) complexes [20][21][22]. Interestingly, these new copper-based complexes have shown excellent activity in the [3 + 2] cycloaddition reaction of azides/sulfonyl azides and alkynes (Scheme 1, right) [22

• 6 was also shown to be active in water and in 1,4-dioxane. Based on these results, a reaction scope was conducted under solvent-free conditions, in air, using 1 mol % of [Cu(Triaz)2]BF4 6 (Scheme 3). Functionalised azides were reacted with phenylacetylene and diisopropylamine resulting in good to

• shown applicable to phosphoryl azides; and reaction of phenylacetylene with diisopropylamine and diphenylphosphoryl azide leads to the formation of the corresponding phosphorylamidine product [34] in good yield (Scheme 7), using 2 mol % of catalyst under mild conditions (solvent-free, room temperature

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

• -phosphine ligands of type 136 were prepared by reacting phosphoacetylene 134 with different alkyl azides to generate the borane-protected ligand 135. The protection is necessary because it prevents the formation of iminophosphorane during the click reaction. The click-phosphine ligands 136 can be liberated

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

• "click" chemistry [16][17][18] of azides and alkynes catalyzed by Cu(I) salts, the CuAAC reaction. Self-assembling properties were not observed for any of the prepared monotriazoles, namely the 4-substituted 1-glucopyranosyltriazoles 1a–g and 2a–g (Scheme 1) [15]. However, most ditriazoles 7a–g and 8a–g

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

• zinc from the coordination sphere of the porphyrin macrocycle and gave the free base maleimide porphyrin 6 in a quantitative yield. A successful formation of the fluorinated porphyrin azides 3a and 3b allowed their utility as intermediates in the further porphyrin core functionalisation especially with

• 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

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

• ][13]. The approach required five isolations only. Unlike Magano [1], the authors could not avoid the use of the potentially explosive azide chemistry. The azide intermediate was not isolated to address the safety concerns posed by azides. Positively, their approach was characterised by low catalyst

• . NaN3 proved to be the best azidating agent (Figure 18). It is evident that the application of ionic bonded azides (NaN3 and TBAA) gave almost similar conversion, 100% and 93%, respectively. Whilst the use of covalently bonded azides (DPPA and TMSA) resulted in lower conversions, 84% and 81

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

• 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

A metal-free approach for the synthesis of amides/esters with pyridinium salts of phenacyl bromides via oxidative C–C bond cleavage

• Kesari Lakshmi Manasa,
• Yellaiah Tangella,
• Namballa Hari Krishna and
• Mallika Alvala

Beilstein J. Org. Chem. 2019, 15, 1864–1871, doi:10.3762/bjoc.15.182

• [6][7], anhydrides [8], esters [9], and acyl azides [10] with amines by employing coupling reagents [11]. Alternative protocols include the Staudinger–Vilarrasa reaction [12], Schmidt reaction [13][14], Beckmann rearrangement [15], aminocarbonylation of aryl halides [16], Staudinger ligation [17

• -workers also demonstrated a transition metal-free aerobic oxidative cleavage of C–C bonds of phenacyl azides employed in the construction of amides utilizing benzylamines [41]. Herein we wish to report a metal-free C(CO)–C(α) bond cleavage of pyridinium salts of phenacyl bromides for the facile synthesis

N-(1-Phenylethyl)aziridine-2-carboxylate esters in the synthesis of biologically relevant compounds

• Iwona E. Głowacka,
• Aleksandra Trocha,
• Andrzej E. Wróblewski and
• Dorota G. Piotrowska

Beilstein J. Org. Chem. 2019, 15, 1722–1757, doi:10.3762/bjoc.15.168

• (Scheme 32) [85]. The reaction involved a nucleophilic displacement at more hindered C2 with inversion of configuration to form the azido ester (2S,1'R)-126 which was transformed into (S)-125 in usual way. However, since amines can be obtained from azides by a Staudinger reaction the ester (2S,1'R)-126

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• heterocycles. Pyridinium ylides used as 1,3-dipoles in this protocol were synthesized by the reaction of pyridines with α-bromo ketones (Scheme 41). The protocol was applicable to a series of EW and EDGs on phenacyl azides. However, the reaction was not successful with ethyl azidoacetate. On the other hand, EW

Synthesis of functionalized diazocines for application as building blocks in photo- and mechanoresponsive materials

• Widukind Moormann,
• Daniel Langbehn and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 727–732, doi:10.3762/bjoc.15.68

• deprotection with TiCl4 the hydroxy-functionalized diazocines 4a and 4b were obtained [32]. The hydroxy groups in 4a and 4b were successfully converted into azides using 2-azido-1,3-dimethylimidazolinium hexafluorophosphate (ADMP) and DBU [33]. The synthesis was completed with a Staudinger reaction to obtain

Cyclopropene derivatives of aminosugars for metabolic glycoengineering

• Jessica Hassenrück and
• Valentin Wittmann

Beilstein J. Org. Chem. 2019, 15, 584–601, doi:10.3762/bjoc.15.54

• , azides and alkynes can be visualized by the Staudinger ligation [8] or the azide–alkyne cycloaddition, that can be performed either copper-catalyzed [9][10] or strain-promoted [11][12]. Another type of reporter group that has been proven to be a valuable tool are electron-rich or strained alkenes, that

Low-budget 3D-printed equipment for continuous flow reactions

• Jochen M. Neumaier,
• Amiera Madani,
• Thomas Klein and
• Thomas Ziegler

Beilstein J. Org. Chem. 2019, 15, 558–566, doi:10.3762/bjoc.15.50

• glycosides 3–7 were obtained. To the best of our knowledge similar cascade flow glycosylations have not been described in the literature so far. Finally, the herein developed flow system devices could also be applied to the continuous flow preparation of glycosyl azides. For example, we were able to convert

Synthesis and fluorescent properties of N(9)-alkylated 2-amino-6-triazolylpurines and 7-deazapurines

• Andrejs Šišuļins,
• Jonas Bucevičius,
• Yu-Ting Tseng,
• Irina Novosjolova,
• Kaspars Traskovskis,
• Ērika Bizdēna,
• Huan-Tsung Chang,
• Sigitas Tumkevičius and
• Māris Turks

Beilstein J. Org. Chem. 2019, 15, 474–489, doi:10.3762/bjoc.15.41

• )-substitution product 6b as the major isomer. To the best of our knowledge, this is the first report on such regioselectivity involving combination of 2,6-diazidopurines and N-nucleophiles. It should be noted that in solution, azides 6 exist in equilibrium between the azidopurine and tetrazolopurine forms. This

Sigmatropic rearrangements of cyclopropenylcarbinol derivatives. Access to diversely substituted alkylidenecyclopropanes

• Guillaume Ernouf,
• Jean-Louis Brayer,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2019, 15, 333–350, doi:10.3762/bjoc.15.29

• ]. Alkylidene(aminocyclopropane) derivatives constitute another interesting class of heterosubstituted alkylidenecyclopropanes which have been previously synthesized by a Curtius rearrangement of acyl azides derived from alkylidenecyclopropane carboxylic acids [43] or by elimination reactions applied to

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

Copper(I)-catalyzed tandem reaction: synthesis of 1,4-disubstituted 1,2,3-triazoles from alkyl diacyl peroxides, azidotrimethylsilane, and alkynes

• Muhammad Israr,
• Changqing Ye,
• Munira Taj Muhammad,
• Yajun Li and
• Hongli Bao

Beilstein J. Org. Chem. 2018, 14, 2916–2922, doi:10.3762/bjoc.14.270

• from alkyl diacyl peroxides, azidotrimethylsilane, and terminal alkynes is reported. The alkyl carboxylic acids is for the first time being used as the alkyl azide precursors in the form of alkyl diacyl peroxides. This method avoids the necessity to handle organic azides, as they are generated in situ

• , making this protocol operationally simple. The Cu(I) catalyst not only participates in the alkyl diacyl peroxides decomposition to afford alkyl azides but also catalyzes the subsequent CuAAC reaction to produce the 1,2,3-triazoles. Keywords: alkyl diacyl peroxides; azidotrimethylsilane; click reaction

• ], derived from the Huisgen’s 1,3-dipolar cycloaddition of azides and alkynes [22], has conceivably emerged as the premier example of click chemistry. Generally, organic azides are used as the azido source in most of the CuAAC reactions (Scheme 1a) [23]. However, the organic azides with low molecular weight

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

• intermediate 3-nitro-2H-chromenes with organic azides in a one-pot two-step sequence. The triazolochromenes were formed with complete regioselectivity and new biologically relevant structures were synthesized via extension of the developed procedure and via postfunctionalization. The mechanochemical synthesis

• nitroacetate and organic azides, in which the synthesis of both triazolocoumarin regioisomers was accomplished [33]. Interestingly, the expected regioisomer was not observed in the case of the in situ formed 3-nitrocoumarins. Hence, in our continued exploration towards novel multicomponent reactions for the

• assembly of triazole-fused (hetero)cycles [24][33][34][35][36][37][38][39][40][41][42], we opted to develop a new one-pot two-step three-component reaction starting from salicylaldehydes, nitroalkenes and organic azides, without isolation of the intermediate 3-nitrochromenes, in a regioselective manner and

Catalyst-free synthesis of 4-acyl-NH-1,2,3-triazoles by water-mediated cycloaddition reactions of enaminones and tosyl azide

• Lu Yang,
• Yuwei Wu,
• Yiming Yang,
• Chengping Wen and
• Jie-Ping Wan

Beilstein J. Org. Chem. 2018, 14, 2348–2353, doi:10.3762/bjoc.14.210

• numerous organic compounds [24][25][26][27][28]. The amazingly rapid and broad permeation of 1,2,3-triazoles to multidisciplinary areas can majorly be attributed to the occurrence of robust synthetic methods toward this heterocycle. The copper-catalyzed click [3 + 2] cycloaddition of azides and alkynes [29

• development of these metal-catalyzed cycloaddition strategies [33][34][35]. Alongside the vast progress happened in MAAC-based 1,2,3-triazole synthesis, the past decade has witnessed the emergence of another powerful cycloaddition tool for the 1,2,3-triazole synthesis: the metal-free cycloaddition of azides

• cycloaddition of azides with activated dipolarophiles such as strained cyclic alkynes, enamines, enolates, electron-deficient olefins, ylides, iminium cations and alkyne anions, etc., have been identified as reliable approaches to access 1,2,3-triazole scaffolds with multiple substitution patterns [39][40][41

Synthesis of new p-tert-butylcalix[4]arene-based polyammonium triazolyl amphiphiles and their binding with nucleoside phosphates

• Vladimir A. Burilov,
• Guzaliya A. Fatikhova,
• Mariya N. Dokuchaeva,
• Ramil I. Nugmanov,
• Diana A. Mironova,
• Pavel V. Dorovatovskii,
• Victor N. Khrustalev,
• Svetlana E. Solovieva and
• Igor S. Antipin

Beilstein J. Org. Chem. 2018, 14, 1980–1993, doi:10.3762/bjoc.14.173

• (CuAAC) reaction [28]. An alternative way is the functionalization of calix[4]arenes by terminal alkynyl groups. However, in this case further transformations by CuAAC reactions are limited mainly due to the fact that low molecular weight organic azides, especially containing less than 3 carbon atoms are

• appear as a singlet at 6.29 ppm. The signals of the bridge methylene protons appear as two doublets at 4.39–4.40 and 3.09–3.10 ppm. The presence of the azide groups was confirmed by valence asymmetric bond vibrations at 2109 cm−1 in the IR spectra of 4 and 8. The MALDI mass spectra of all obtained azides

Artificial bioconjugates with naturally occurring linkages: the use of phosphodiester

• Takao Shoji,
• Hiroki Fukutomi,
• Yohei Okada and
• Kazuhiro Chiba

Beilstein J. Org. Chem. 2018, 14, 1946–1955, doi:10.3762/bjoc.14.169

• , artificial functional groups such as alkynes or azides must be pre-installed into the respective biomolecules. Thus generated linkages are also artificial, possibly causing significant perturbation from their native forms, which generally affect bioactivities negatively. Arguably, naturally occurring