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

• esterified pyridines 29 in moderate to high yield. It is worth noting that 1,3-enynes 28 bearing internal alkyne moieties were not tolerated as substrates. In 2016, Aïssa and co-workers reported a nickel-catalyzed [4 + 2]-cycloaddition of 3-azetidinones 30 with 1,3-enynes 31 for the synthesis of 3‑hydroxy

• -4,5-alkyl-substituted pyridines 33 (Scheme 11) [53]. The transformation involved a two-step sequence of successive reactions: Firstly, the nickel-catalyzed [4 + 2]-cycloaddition of 1,3-enynes 31 and N-Ts-substituted 3-azetidinone 30 afforded dihydropyridinones 32 in good yield. The next step involved

• chalcogenoamination. The derivatization of 5‑selenyl- and 5-sulfenyl-substituted nicotinates. The tandem reaction of nitriles, Reformatsky reagents, and 1,3-enynes. Nickel-catalyzed [4 + 2]-cycloaddition of 3-azetidinones with 1,3-enynes. Electrophilic iodocyclization of 2-nitro-1,3-enynes to pyrroles. Electrophilic

Efficient synthesis of polyfunctionalized carbazoles and pyrrolo[3,4-c]carbazoles via domino Diels–Alder reaction

• Ren-Jie Fang,
• Chen Yan,
• Jing Sun,
• Ying Han and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2021, 17, 2425–2432, doi:10.3762/bjoc.17.159

• that this acid-catalyzed cycloaddition reaction proceeded through a concerted Diels–Alder reaction mechanism. The acid-catalyzed Diels–Alder reaction afforded a mixture of two diastereoisomers, which decreased the synthetic value of the reaction. Thus, after the first step reaction, a DDQ

Synthesis and antimicrobial activity of 1H-1,2,3-triazole and carboxylate analogues of metronidazole

• Satya Kumar Avula,
• Syed Raza Shah,
• Khdija Al-Hosni,
• Muhammad U. Anwar,
• Rene Csuk,
• Biswanath Das and
• Ahmed Al-Harrasi

Beilstein J. Org. Chem. 2021, 17, 2377–2384, doi:10.3762/bjoc.17.154

• . The structure of metronidazide 3 was unambiguously confirmed by single crystal X-ray analysis (Figure 3). The next step was carried out by using “click” chemistry involving the 1,3-dipolar cycloaddition reaction between metronidazide 3 and alkyne derivative 4a in the presence of CuI and Hünig’s base

Synthesis of phenanthridines via a novel photochemically-mediated cyclization and application to the synthesis of triphaeridine

• Songeziwe Ntsimango,
• Kennedy J. Ngwira,
• Moira L. Bode and
• Charles B. de Koning

Beilstein J. Org. Chem. 2021, 17, 2340–2347, doi:10.3762/bjoc.17.152

• ], rhodium-mediated alkyne [2 + 2 + 2] cycloaddition reactions [3], and the palladium-catalysed aerobic domino Suzuki coupling/Michael addition reaction [4]. The most attractive and common strategies to phenanthridines rely on intramolecular cyclizations of various ortho-functionalized biaryl precursors

Synthesis of O⁶-alkylated preQ₁ derivatives

• Laurin Flemmich,
• Sarah Moreno and
• Ronald Micura

Beilstein J. Org. Chem. 2021, 17, 2295–2301, doi:10.3762/bjoc.17.147

• -diaminopyrimidin-4-one to the nitroolefin 2-[(2E)-3-nitroprop-2-en-1-yl]-1H-isoindole-1,3(2H)-dione [23]. Finally, Carell reported a cycloaddition route relying on α-brominated 3-phthalimidopropanal and diaminopyrimidin-4-one [24][25]. We further optimized this path for the synthesis of 15N-labeled prequeuosine

(Phenylamino)pyrimidine-1,2,3-triazole derivatives as analogs of imatinib: searching for novel compounds against chronic myeloid leukemia

• Luiz Claudio Ferreira Pimentel,
• Lucas Villas Boas Hoelz,
• Henayle Fernandes Canzian,
• Frederico Silva Castelo Branco,
• Andressa Paula de Oliveira,
• Vinicius Rangel Campos,
• Floriano Paes Silva Júnior,
• Rafael Ferreira Dantas,
• Jackson Antônio Lamounier Camargos Resende,
• Anna Claudia Cunha,
• Nubia Boechat and
• Mônica Macedo Bastos

Beilstein J. Org. Chem. 2021, 17, 2260–2269, doi:10.3762/bjoc.17.144

• )pyrimidine-pyridine (PAPP) group as a pharmacophoric fragment, and these compounds were biologically evaluated. The synthesis of twelve new compounds was performed in three steps and assisted by microwave irradiation in a 1,3-dipolar cycloaddition to obtain 1,2,3-triazole derivatives substituted on carbon C

• in the docking studies. Keywords: chronic myeloid leukemia; 1,3-dipolar cycloaddition; imatinib; (phenylamino)pyrimidine-pyridine; 1,2,3-triazole; Introduction Changes in tyrosine kinase proteins (TKPs), either by mutation or chromosomal translocation, can turn them into potent oncogenes

• developed by Sharpless and collaborators, to the Huisgen cycloaddition (a 1,3-dipolar cycloaddition reaction to obtain this heterocycle) allowed the regiospecific synthesis of the 1,4-disubstituted isomers with good yields in the presence of copper(I) salts [15][16][17]. Since then, medicinal chemists used

Facile and innovative catalytic protocol for intramolecular Friedel–Crafts cyclization of Morita–Baylis–Hillman adducts: Synergistic combination of chiral (salen)chromium(III)/BF₃·OEt₂ catalysis

• Karthikeyan Soundararajan,
• Helen Ratna Monica Jeyarajan,
• Raju Subimol Kamarajapurathu and
• Karthik Krishna Kumar Ayyanoth

Beilstein J. Org. Chem. 2021, 17, 2186–2193, doi:10.3762/bjoc.17.140

• arrangement would facilitate the intramolecular Friedel–Crafts cyclization of the MBH adducts. Cycloaddition of azomethine imine 7a with 2-substituted-1H-indenes 6b and 6c was attempted to ascertain the structure of the synthesized 1H-indenes (Scheme 3). The azomethine imine, 1-benzylidene-3-oxopyrazolidin-1

• -ium-2-ide (7a) was synthesised at room temperature by treating methyl acrylate, hydrazine hydrate and benzaldehyde in a yield of 67%. On treating the synthesised azomethine imine 7a (1.2 mM) and 2-substituted-1H-indenes 6b and 6c (1 mM) in toluene at 70 °C affords 8a and 8b via [3 + 2] cycloaddition

• reaction at a yield of 61% and 72%, respectively. Encouraged by the outcome of this non-catalytic cycloaddition reaction, similar studies using 2-substituted-1H-indenes (6a–f) with azomethine imines are underway. Conclusion In summary we have developed an efficient synthetic protocol for intramolecular

Enantioenriched α-substituted glutamates/pyroglutamates via enantioselective cyclopropenimine-catalyzed Michael addition of amino ester imines

• Zara M. Seibel,
• Jeffrey S. Bandar and
• Tristan H. Lambert

Beilstein J. Org. Chem. 2021, 17, 2077–2084, doi:10.3762/bjoc.17.134

• Michael adduct to cycloaddition product (Table 1, entry 2). Interestingly, the larger ring-containing catalyst 6 improved this ratio somewhat to 6:1 while retaining the enantiomeric ratio, albeit at the expense of reactivity (Table 1, entry 3). Incorporation of additional unsaturation (catalyst 7

• , stereoselectivity, and selectivity for the Michael addition versus cycloaddition (Figure 2). The optimal substituent in this regard proved to be p-chlorophenyl 1, which resulted in the yield and selectivities using catalyst 5 as already discussed in Table 1. The o-chlorophenyl imine 12 was equally reactive, but led

• carbon, either in a concerted fashion or via subsequent addition of a putative acrylate enolate intermediate, would lead to the cycloaddition byproduct 11 (path b, red and blue dashed lines). It should be noted that cyclopropenimine catalysts do not promote the cyclization of 10 to 11. From this model

A study on selective transformation of norbornadiene into fluorinated cyclopentane-fused isoxazolines

• Zsanett Benke,
• Attila M. Remete and
• Loránd Kiss

Beilstein J. Org. Chem. 2021, 17, 2051–2066, doi:10.3762/bjoc.17.132

• Abstract This work presents an examination of the selective functionalization of norbornadiene through nitrile oxide 1,3-dipolar cycloaddition/ring-opening metathesis (ROM)/cross-metathesis (CM) protocols. Functionalization of commercially available norbornadiene provided novel bicyclic scaffolds with

• selective functionalization of readily available norbornadiene across nitrile oxide cycloaddition/ROM/CM protocols in view of the access of various fluorine-containing molecular entities as well as to explore the chemical behavior of olefin bonds in the reaction with some fluorinated alkene derivatives in

• cycloaddition according to the Mukaiyama method followed by ROM of the major product. All five catalysts provided the desired products to some extent, but HG-1 gave the highest yield of (±)-4: 76%, (±)-5: 75% and (±)-6: 87% [41]. Further functionalization of compounds (±)-4–6 was attempted via CM with a high

Recent advances in the syntheses of anthracene derivatives

• Giovanni S. Baviera and
• Paulo M. Donate

Beilstein J. Org. Chem. 2021, 17, 2028–2050, doi:10.3762/bjoc.17.131

• -cyclotrimerization reaction catalyzed by a cobalt/zinc reagent [40]. With regard to substituted anthracenes, this method consisted of a [2 + 2 + 2] cycloaddition reaction of 1,6-diynes 27 with 4-aryl-2-butyn-1-ols 28 (Scheme 6). The authors converted the resulting benzylic alcohols 29 to the corresponding aldehydes

• substituents on the benzaldeydes 169 [72]. Cycloaddition reactions In 2014, Gao, Li, and their co-workers published a facile strategy to synthesize polysubstituted aromatic compounds from the reaction of quinones or maleimides with β-enamino esters (Scheme 39) [73]. They synthesized anthraquinone derivatives

• 173 in good yield (62–94%) via a cycloaddition/oxidative aromatization sequence involving quinone 171 and substituted β-enamino esters 172 as precursors. They prepared anthraquinone 173a starting from three different β-enamino esters; a less bulky β-enamino ester favored the reaction. The scope of the

Asymmetric organocatalyzed synthesis of coumarin derivatives

• Natália M. Moreira,
• Lorena S. R. Martelli and
• Arlene G. Corrêa

Beilstein J. Org. Chem. 2021, 17, 1952–1980, doi:10.3762/bjoc.17.128

• -hydroxycoumarin (1) with the chiral catalyst 48, as shown in Scheme 15 [48]. The enantioselective synthesis of dihydrocoumarins 51 from an inverse demand [4 + 2] cycloaddition of ketenes 50 with o-quinone methides 49 using carbene catalyst (NHC) 52 was described by Ye and co-workers [49].This transformation

• oxidative [4 + 2] cycloaddition with unsaturated aldehydes 57 [51]. The methodology draws attention for the wide variety of products 58 obtained with moderate to excellent yields and enantiomeric excesses (Scheme 18). Activation via noncovalent bonding Besides the activation mode via a covalent bond, as

• and colleagues proposed an asymmetric [3 + 2] cycloaddition employing a coumarin dipolarophile 43 with azomethine ylides 60 organocatalyzed by quinidine (62) for the formation of fused pyrrolidine compounds through activation of the coumarin substrate by hydrogen bonding [53]. The methodology enabled

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

• [158]. The synthesis started with a cyclopentene derivative, obtained after two steps from a diol via tosylation/displacement strategy with Me2CuLi·LiI. Then, after a Lewis acid-promoted cycloaddition, the alkylation of the α-carbon atom followed by regioselective Baeyer–Villiger oxidation provided the

• ] and batteries [174]. Due to its accessibility, it is well explored in catalysis for many fields, such as cycloaddition reactions [175], polymerization [176], and C–C cross-coupling methods [177]. Several biologically active compounds have been obtained through cobalt catalysis [178][179][180

Sustainable manganese catalysis for late-stage C–H functionalization of bioactive structural motifs

• Jongwoo Son

Beilstein J. Org. Chem. 2021, 17, 1733–1751, doi:10.3762/bjoc.17.122

• conjugative transformations, such as azide–alkyne [3 + 2]-cycloaddition [30][31][32][33][34][35][36][37]. Based on their previous late-stage fluorination studies [22][25], Groves et al. further showcased a manganese(III)–salen-catalyzed azidation process using an aqueous azide solution as a convenient azide

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

• industry. The current review aims to cover a wide literature survey of numerous synthetic strategies. Recent reports (2017–2021) in the field of 1,4,5-trisubstituted 1,2,3-triazoles are emphasized in this current review. Keywords: azides; Click reaction; [3 + 2]‐cycloaddition; fully functionalized 1,2,3

• applications of these five-membered N-heterocycles are the result of both their easy synthetic procedures and ring functionalization [9][31][32]. Typically, 1,2,3-triazole derivatives are prepared via a 1,3-dipolar cycloaddition reaction between azides and alkynes [33]. It is worth noting that the metal

• -catalyzed Huisgen cycloaddition reaction could provide disubstituted 1,2,3-triazoles. The selective introduction of substituents to three different positions on the 1,2,3-triazole frame can notably improve the features of the molecule. Therefore, practical and cost-effective strategies for the selective

Chemical synthesis of C6-tetrazole ᴅ-mannose building blocks and access to a bioisostere of mannuronic acid 1-phosphate

• Eleni Dimitriou and
• Gavin J. Miller

Beilstein J. Org. Chem. 2021, 17, 1527–1532, doi:10.3762/bjoc.17.110

• mannuronic acid building blocks, appropriately modified at the carboxylate C6 position with a bioisosteric tetrazole. Thioglycosides containing a protected C6-tetrazole are accessed from a C6-nitrile, through dipolar cycloaddition using NaN3 with n-Bu2SnO. We also demonstrate access to orthogonally C4

• yield of 50% (compared to 31% in accessing 9 from 7). Nitrile 16 then underwent dipolar cycloaddition with NaN3, converting it to C6-tetrazole thioglycoside 17 in 55% yield. This material was then protected at tetrazole nitrogen in 76% yield using PMBCl to give 18 and 19 (N1-PMB/N2-PMB = 1:1.2) as

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

• spirocyclic 1,4,2-dioxazole derivatives [13][14]. Furthermore, for photochemically generated benzonitrile isopropanide, competitive C=O and C=C additions with 1,4-quinones were observed [15]. On the other hand, the slightly less polar benzonitrile benzylide underwent [3 + 2]-cycloaddition to the C=C bond

• reported in the 1960s [17]. The latter 1,3-dipole was generated thermally from the respective tetrazole derivative 3, and the observed [3 + 2]-cycloadditions occurred chemoselectively to provide fused pyrazoles of the type 4 as exclusive products (Scheme 1). This type of cycloaddition attracted

• -thiadiazoles as the products of [3 + 2]-cycloaddition to the C=S bond [25]. Taking into account that fluorinated heterocycles [31][32][33][34], including pyrazoles [31][35][36], are of great significance for various medicinal and agricultural applications, the development of new methods for the construction of

Synthesis of 1-indolyl-3,5,8-substituted γ-carbolines: one-pot solvent-free protocol and biological evaluation

• Premansh Dudhe,
• Mena Asha Krishnan,
• Kratika Yadav,
• Diptendu Roy,
• Krishnan Venkatasubbaiah,
• Biswarup Pathak and
• Venkatesh Chelvam

Beilstein J. Org. Chem. 2021, 17, 1453–1463, doi:10.3762/bjoc.17.101

• alkaloid ingenine B [20]. The iodine-catalyzed [3 + 3] cycloaddition of indolyl alcohol to enaminones [21] and the thiourea-catalyzed iso-Pictet–Spengler reaction of isotryptamine with aldehydes [22], are some noteworthy contributions to the field. A cascade or domino reaction is an interesting approach

• , alkyl N-arylideneglycinates have attracted much attention in recent years. For instance, the metal-catalyzed asymmetric [3 + 2] cycloaddition of ethyl N-benzylideneglycinates with electron-deficient alkenes has been reported to yield substituted pyrrolidines [30]. Recently, we reported the synthesis of

Double-headed nucleosides: Synthesis and applications

• Vineet Verma,
• Jyotirmoy Maity,
• Vipin K. Maikhuri,
• Ritika Sharma,
• Himal K. Ganguly and
• Ashok K. Prasad

Beilstein J. Org. Chem. 2021, 17, 1392–1439, doi:10.3762/bjoc.17.98

• -ethynylpyrene (40) under copper-catalyzed alkyne–azide cycloaddition (CuAAC) reaction conditions to yield the double-headed nucleoside 41 (Scheme 10) [23]. The double-headed nucleoside 41 was phosphitylated and then incorporated into oligonucleotides and was found to form highly stable DNA duplexes and three

• nucleosides were further reacted with propargylated nucleobases through a copper-catalyzed azide–alkyne cycloaddition (CuAAC) reaction followed by treatment with methanolic ammonia to give the C-3′-substituted double-headed ribofuranonucleosides 46a–c and 50a–e (Scheme 11) [36]. The double-headed nucleosides

• cycloaddition (CuAAC) reaction conditions to yield the double-headed nucleosides 154a and 154b, respectively (Scheme 39) [24]. The synthesized double-headed nucleosides 151a–d and 154a,b were phosphitylated, incorporated into oligonucleotides and characterized with respect to thermal denaturation, enzymatic

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

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

• Joseane A. Mendes,
• Paulo R. R. Costa,
• Miguel Yus,
• Francisco Foubelo and
• Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

• stereoselective synthesis is especially interesting, highlighting the 1,3-dipolar cycloaddition reactions with azomethine ylides as an example of transformation that take place with great stereocontrol, and allow the synthesis of polyfunctionalized pyrrolidines in a single reaction step [91][92]. On the other

• took place to the Re face of imines with (Z,SS)-configuration (Scheme 27). The cycloaddition of chiral sulfinyl imines (RS)-14 with 2-(trimethysilylmethyl)allyl acetate (91) could also be promoted by Pd(0) to give methylenepyrrolidines 92. The group of Stockman demonstrated that Pd(PPh3)4 was the best

• stereochemical outcome of the cyclization considering that the stereoinduction is derived from the dipole–dipole repulsion of the sulfinyl imine, which places the tert-butyl group on the Si face, and thus the cycloaddition occurs from the less sterically hindered Re face. The cyclization process worked also in

Synthetic accesses to biguanide compounds

• Oleksandr Grytsai,
• Cyril Ronco and
• Rachid Benhida

Beilstein J. Org. Chem. 2021, 17, 1001–1040, doi:10.3762/bjoc.17.82

• equivalents of the carbodiimide in the reaction with N,N’-disubstituted guanidines resulted in the formation of 1,2-dihydro-1,3,5-triazine derivatives as the main products of the cycloaddition reaction [82]. They also showed that increasing the amount of the carbodiimide to 3 equivalents led to excellent

Prins cyclization-mediated stereoselective synthesis of tetrahydropyrans and dihydropyrans: an inspection of twenty years

• Asha Budakoti,
• Pradip Kumar Mondal,
• Prachi Verma and
• Jagadish Khamrai

Beilstein J. Org. Chem. 2021, 17, 932–963, doi:10.3762/bjoc.17.77

• based on DFT calculations. A different [2 + 2]-cycloaddition process was suggested to rationalize the observed OH-selectivity. In 2015, Padrón and co-workers also reported the Prins cyclization catalyzed by a Fe(III) and trimethylsilyl halide system for the synthesis of all-cis-2,4,6-trisubstituted THP

• [107]. As reported previously by Feng et al. [106], two mechanistic pathways via the classical oxocarbenium route and [2 + 2]-cycloaddition were considered for DFT calculations. Experimental and DFT studies suggested the preference of a classical oxocarbenium route over the [2 + 2]-pathway for those

Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects

• Shivani Gulati,
• Stephy Elza John and
• Nagula Shankaraiah

Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71

• -MCRs and their mechanistic insights over the past decade and shed light on its advantage over the conventional approach. Keywords: cycloaddition; Knoevenagel condensation; Michael addition; microwave; multicomponent reactions; Introduction Recently, organic chemists are focussed to develop

• [29][30], focusing on the synthetic aspect of five, six, seven and dicyclic structures. Later in 2013, Gupta et al. compiled reports of microwave-assisted cross-coupling, MCR with few cycloaddition reactions [31]. During the course of writing this review, we realized the very presence of two reviews

• enaminone B. Later, the successive Michael addition of A and enaminone B followed by an intramolecular cycloaddition with concomitant dehydration delivered the final product 7 (Scheme 2). In 2018, our research group [39] contemplated and developed an expeditious process for the synthesis of phenanthrene

Synthetic reactions driven by electron-donor–acceptor (EDA) complexes

• Zhonglie Yang,
• Yutong Liu,
• Kun Cao,
• Xiaobin Zhang,
• Hezhong Jiang and
• Jiahong Li

Beilstein J. Org. Chem. 2021, 17, 771–799, doi:10.3762/bjoc.17.67

• the fact that diamine can condense with the enol substrate, forming an imine-ion intermediate absorbing in the visible region. The direct excitation of the intermediate leads to a charge-transfer excited state, completing the stereocontrolled intermolecular cycloaddition reaction with a good ratio of

• ] developed a visible-light-induced [3 + 2] cycloaddition reaction between glycine derivatives 57 and aryl epoxides 58, which can efficiently prepare a series of multisubstituted 1,3-oxazolidines 59 at room temperature (Scheme 20). The strategy can be applied smoothly to an extensive range of glycine

Synthesis of β-triazolylenones via metal-free desulfonylative alkylation of N-tosyl-1,2,3-triazoles

• Soumyaranjan Pati,
• Renata G. Almeida,
• Eufrânio N. da Silva Júnior and
• Irishi N. N. Namboothiri

Beilstein J. Org. Chem. 2021, 17, 762–770, doi:10.3762/bjoc.17.66

• synthesis of new functionalized 1,2,3-triazoles. Keywords: azoles; cycloaddition; enones; heterocycles; 1,2,3-triazoles; Introduction 1,2,3-Triazoles are significant non-natural heterocyclic scaffolds with extensive applications in biochemistry, agrochemistry and materials chemistry [1][2][3][4][5]. This

• precursors in denitrogenative transannulation reactions under metal-catalysed conditions to form other heterocycles such as functionalized pyrroles, imidazoles and pyridines (Scheme 1b) [11][12][13]. The traditional method for the synthesis of triazole unit is the Huisgen 1,3-dipolar cycloaddition between

• Meldal have independently developed a copper-catalysed azide–alkyne cycloaddition that accelerated the rate of the reaction and allowed the selective preparation of 1,5-disubstituted 1,2,3-triazoles [16][17][18][19]. As noted above, a wide range of methods are available in the literature for the