Ultrasonic-assisted unusual four-component synthesis of 7-azolylamino-4,5,6,7-tetrahydroazolo[1,5-a]pyrimidines

• Yana I. Sakhno,
• Maryna V. Murlykina,
• Oleksandr I. Zbruyev,
• Anton V. Kozyryev,
• Svetlana V. Shishkina,
• Dmytro Sysoiev,
• Vladimir I. Musatov,
• Sergey M. Desenko and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2020, 16, 281–289, doi:10.3762/bjoc.16.27

• Republic 10.3762/bjoc.16.27 Abstract Four-component reactions of 3-amino-1,2,4-triazole or 5-amino-1H-pyrazole-4-carbonitrile with aromatic aldehydes and pyruvic acid or its esters under ultrasonication were studied. Unusual for such a reaction type, a cascade of elementary stages led to the formation of

• 7-azolylaminotetrahydroazolo[1,5-a]pyrimidines. Keywords: 5-amino-1H-pyrazole-4-carbonitrile; 3-amino-1,2,4-triazole; 7-azolylaminotetrahydroazolo[1,5-a]pyrimidines; heterocycle; multicomponent reaction; ultrasonication; Introduction Tetrahydropyrimidines are heterocycles of high pharmacological

• . Therefore, the present work is devoted to the study of multicomponent reactions involving 3-amino-1,2,4-triazole or 5-aminopyrazoles, aromatic aldehydes, and pyruvic acid or its esters under ultrasonication. Results and Discussion It was discovered that MCRs involving 3-amino-1,2,4-triazole or 5-amino-1H

Synthesis of 4-(2-fluorophenyl)-7-methoxycoumarin: experimental and computational evidence for intramolecular and intermolecular C–F···H–C bonds

• Vuyisa Mzozoyana,
• Fanie R. van Heerden and
• Craig Grimmer

Beilstein J. Org. Chem. 2020, 16, 190–199, doi:10.3762/bjoc.16.22

• aromatic triazole foldmers [37]. In their study, using crystallographic and DFT data, they concluded that their folded conformers are held by C–F···H–C hydrogen bonds. To further these studies, we have synthesized a fluorine-containing phenylcoumarin in order to study the fluorine-hydrogen bond. The

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

• chemistry, anion recognition, organocatalysis, materials science and tuning of biomolecular systems [17][18][19][20][21][22][23][24][25][26][27]. 1,2,3-Triazole-based XB-donors, such as 5-iodo-1,2,3-triazoles A [28][29][30][31][32][33] and 5-iodo-1,2,3-triazolium B [34][35][36][37] (Figure 1), are promising

• aldehydes [44]. Despite a variety of XB donors based on 1,2,3-triazole have been reported, no 4,5-diido-1,2,3-triazolium salts have been reported for an XB interaction. Herein, we report the synthesis and characterization of 4,5-diido-1,2,3-triazolium D with different anions. The crystal structures of these

• understand the 1,2,3-triazole based XB donors, model 1,2,3-triazole A, 1,2,3-triazolium B, 1,2,3-triazolylidene complex C-CuI and diiodotriazolium D were calculated by DFT calculations (Figure 9). The calculation results show that σ holes in diiodotriazolium D are mainly located in the elongation of two C–I

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

• stacking interactions, in addition to hydrogen bonding, with the aromatic rings adopting a high degree of parallelism, as seen in crystal packings and ECD data. Furthermore, π–bromine interactions between the bromine atom of the aryl substituents and the triazole units might also contribute to an overall

• stabilization of the supramolecular aggregation of bis(4-bromophenyl)triazoles. The trans or cis spatial disposition of the triazole rings is highly important for gelation, with the cis configuration having higher propensity. Keywords: circular dichroism; cis/trans configuration; gels; triazole; X-ray

• low-molecular-weight gelators have potential applications in high-tech materials [1][2][3] and biomedical sciences [3][4][5][6]. Triazole derivatives have shown excellent gelation properties [7][8][9][10], in addition to a broad range of biological activities [11][12][13][14]. During the synthesis and

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

• represent an important class of nitrogen-containing biologically active compounds which exhibit various biological properties, such as antiviral, antibacterial and anticancer, etc. [55][56][57][58]. Recently, the use of 1,2,3-triazole derivatives as drug candidates has been increased for clinical therapy of

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

• ) or Ni(II) with N-propargylmaleimide via the CuAAC click reaction to afford fluorinated porphyrin–triazole–maleimide conjugates. New maleimide derivatives were isolated in reasonable yields and identified by UV–vis, 1H NMR, 19F NMR spectroscopy and mass-spectrometry. Keywords: chlorin; maleimide

• 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

• -propargylmaleimide [44] was carried out successfully in CH2Cl2 and the fluorinated porphyrin–triazole–maleimide conjugates 7a and 7b were obtained in 54–58% yield. In these conjugates the tetrafluorophenyl units of the porphyrin macrocycle where separated from maleimides with 1,2,3-triazole spacer groups. Removal 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

• in the literature supporting the chelation of metal centers by a tetrazole ring during the C–H activation processes, in which the tetrazole may also act as directing group [55][56][57][58][59][60][61]. The closely related triazole ring has also been used for the C–H modification of amino acids and

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

• accessible by variation of the binucleophilic component 1 (instead of 1, 3-amino-1,2,4-triazole, 2-aminobenzimidazole, 3-aminopyrazoles, 4-amino-1,2,3-triazoles, etc. can be used [13]). However, a relatively low reactivity of amine 1 due to the electron deficiency of the tetrazole ring has been reported

Thermal stability of N-heterocycle-stabilized iodanes – a systematic investigation

• Andreas Boelke,
• Yulia A. Vlasenko,
• Mekhman S. Yusubov,
• Boris J. Nachtsheim and
• Pavel S. Postnikov

Beilstein J. Org. Chem. 2019, 15, 2311–2318, doi:10.3762/bjoc.15.223

• pseudocyclic iodosobenziodoxolone 1. The decomposition of 1 has a two-step character and includes initial endothermic melting at 185.1 °C followed by exothermal decomposition at 206.8 °C with an ΔHdec of 72.9 kJ/mol (Figure 3a). For the pseudocyclic NHI 2 with a triazole ligand no initial melting process was

• detected. Instead the solid degraded with a pronounced and narrow (less than 1 °C) exothermal peak at 120.8 °C (Figure 3b). Decomposition was associated with a higher ΔHdec of 116.3 kJ/mol. A similar decomposition behavior was observed for the other triazole-containing pseudocyclic NHIs 3–5. Introduction

• of a methyl-substituent at C5 of the triazole 3 was accompanied by an increased decomposition enthalpy (ΔHdec = 125.1 kJ/mol). However, thermal stability as indicated by a higher Tpeak, significantly increased. Methyl substitution at N2 resulted in an even higher Tpeak at 152.4 °C and a decreased

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

• catalyzed by a Cu(I) ion, was regarded as the representative reaction [15][16]. This reaction occurs even in aqueous media, the chemical yield is always high, and the regiochemical structure of the product is always 1,4-disubstituted triazole. Cu(I)-catalyzed Huisgen cyclization proceeds by the formation of

• photochromic diarylethenes containing triazole groups have been reported [20][21][22][23][24][25][26][27][28][29][30][31], all of them use the triazole ring as the linker of the second functional molecule with the diarylethene core. To the best of our knowledge, no diarylethenes or terarylenes possessing the

• triazole ring as one of the components of the hexatriene moiety has been reported to date. Accordingly, we decided to employ a Ru(I) catalyst to synthesize 4,5-diaryl-1-substituted-1,2,3-triazoles 1o–3o as possible photochromic compounds (Scheme 2). Results and Discussion Molecular design and synthesis As

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

• imidazoles [8][9], polypyrroles [10][11], and indole moieties [12][13], as part of supramolecular receptors, triazole heterocycles containing macrocycles have recently been introduced as new host molecules for the selective recognition of ions, mechanically interlocked molecules (MIMs), supramolecular

• candidates for amide bond surrogates. Interestingly, 1,2,3-triazole units can act as sensors for both anions and cations via different binding mechanisms [16][17]. The heterocyclic ring N2 and N3 atoms could realize the selective recognition of the cations whereas the C5–H···anions electrostatic interaction

• -triazole units to more electrophilic 1,2,3-triazolium units by influencing both hydrogen bonding-like and anion–π interactions. Moreover, halogen bond (XB) and chalcogen bond (ChB) interactions (see Figure 1) also been applied for the selective detection of anions by exchanging C5–H protons with halogens

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

• our case column chromatography was only used once (to purify the monoazidocalix[4]arene 7), whilst the other procedure needed chromatography at each step. Introduction of the triazole moiety onto the upper rim of the calix[4]arene was then achieved with a copper-catalyzed Huisgen 1,3-dipolar

Synthesis of a [6]rotaxane with singly threaded γ-cyclodextrins as a single stereoisomer

• Jason Yin Hei Man and
• Ho Yu Au-Yeung

Beilstein J. Org. Chem. 2019, 15, 1829–1837, doi:10.3762/bjoc.15.177

• . The 1H spectrum of 6R contains one set of sharp signals, suggesting that the [6]rotaxane is adopting a relatively rigid and symmetrical structure in solution (Figure 2a). NOE cross peaks between the triazole and CB[6] protons, and also Ha of the anthracene stoppers and CB[6] protons were observed

• , suggesting that the two CB[6] are interlocking at the triazole which is consistent with the strong binding of the CB[6] to the ammoniums (Figure S18 in Supporting Information File 1). Due to the severe peak overlapping in the aliphatic region at 3.5–4.5 ppm, NOE cross peaks in that regions cannot be

• specific and orthogonal interactions of the macrocycles with different part of the axle. More interestingly, only one set of signals was observed for both the triazole and CB[6] protons in 6R. This observation is suggesting that 1) 6R is adopting a structure that the CB[6] at the termini are far from the

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

• )-5a was reacted with 3-bromo-5-methoxy-1H-1,2,4-triazole (128) to give N-protected bicyclic amino ester 129 which was next converted into (S)-(+)-127 in two standard steps (Scheme 33) [17]. Its enantiomer was prepared from (2R,1′S)-5a. Lacosamide ((R)-130) is a derivative of ᴅ-serine and has found

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

• product. This was an unprecedented report for the synthesis of a library of targeted moieties using a nano-click catalyst. The triazole precursor was also synthesized by the group using nano-copper oxide in an aqueous medium. The reaction has well tolerated variedly substituted starting materials whether

Synthesis of ([1,2,4]triazolo[4,3-a]pyridin-3-ylmethyl)phosphonates and their benzo derivatives via 5-exo-dig cyclization

• Aleksandr S. Krylov,
• Artem A. Petrosian,
• Julia L. Piterskaya,
• Nataly I. Svintsitskaya and
• Albina V. Dogadina

Beilstein J. Org. Chem. 2019, 15, 1563–1568, doi:10.3762/bjoc.15.159

• , hypervalent iodine reagents, etc. The synthetic methods towards diverse [1,2,4]triazolo[3,4-a]pyridines have been reviewed in detail [12][13]. It should be noted that the use of acetylene species to create this heterocycle (including triazole ring) is presented only by few examples. There has been reported

• the phosphoryl unit resonating at 3.75–4.19 ppm with 2JHP = 20 Hz. At lower field, the signals of 6 protons of the (iso)quinoline rings are present at 7.1–8.7 ppm. In the 13C NMR spectra, the methylene and methine carbons of the triazole ring resonate as doublet signals with characteristic constants

• available N-unsubstituted 2-hydrazinylpyridines and 2(1)-hydrazinyl(iso)quinolines. Due to the presence of the fused [1,2,4]triazole hetaryl pharmacophore fragment and a phosphoryl group in the obtained compounds they are of great interest as promising substances with potential biological activity

Stereo- and regioselective hydroboration of 1-exo-methylene pyranoses: discovery of aryltriazolylmethyl C-galactopyranosides as selective galectin-1 inhibitors

• Alexander Dahlqvist,
• Axel Furevi,
• Niklas Warlin,
• Hakon Leffler and
• Ulf J. Nilsson

Beilstein J. Org. Chem. 2019, 15, 1046–1060, doi:10.3762/bjoc.15.102

• ; galectin-1; hydroboration; inhibition; selective; triazole; Introduction Galectins are defined by a typically about 130 amino acid carbohydrate recognition domain (CRD) that binds to carbohydrates with at least one β-galactose subunit within a binding pocket large enough to accommodate a tetrasaccharide

• those of lactose and LacNAc for galectin-3 and also to have selectivity over other galectin-1 [22][23]. Later, combining non-natural thiophenyl aglycons with C3-triazole groups at D-galactose led to the discovery of high affinity and selective galectin-3 inhibitors [24]. In this work, we present a

• -Glu71 groove may, in addition to a more favorable steric complementarity, benefit from the electron-poor triazole hydrogen sampling positions close to the Glu71 carboxylate and the electron-rich triazole nitrogens sampling positions close to the rim of Trp68 side chain. This hypothesis may also explain

New α- and β-cyclodextrin derivatives with cinchona alkaloids used in asymmetric organocatalytic reactions

• Iveta Chena Tichá,
• Simona Hybelbauerová and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2019, 15, 830–839, doi:10.3762/bjoc.15.80

• as the promoter (not in a catalytic amount) of a Henry reaction and obtained the product with 99% ee. Subsequently, Doyagüez et al. [17] attached L-proline to β-CD via different linkers (including a triazole linker) and used the resulting organocatalysts in an aldol reaction in water, albeit with a

• triazole (8.21 ppm), thus confirming the successful attachment of the cinchona alkaloid to the CD skeleton through the CuAAC click reaction. The second part of the 1H NMR spectrum comprises the resolved signal for the double bond on the quinuclidine skeleton of the cinchona alkaloid (5.93 ppm). The third

• identified in the region around 2.00–1.20 ppm. Subsequently, 13C NMR, DEPT-edited HSQC and HMBC spectra also confirmed the substitution on the primary rim of the CD skeleton (Figure 4). The C-6 atom of the substituted glucose unit is correlated with the hydrogen signal of the triazole ring (50.41 ppm of C-6I

An efficient and concise access to 2-amino-4H-benzothiopyran-4-one derivatives

• Peng Li,
• Yongqi Wu,
• Tingting Zhang,
• Chen Ma,
• Ziyun Lin,
• Gang Li and
• Haihong Huang

Beilstein J. Org. Chem. 2019, 15, 703–709, doi:10.3762/bjoc.15.65

• in the presence of bases such as NaH, K2CO3, etc. However, for this reaction an adjacent electron-withdrawing group such as a carbonyl or triazole group is required at the 3-position of the thiochromone ring (method D and E, Scheme 1) [3][4]. Very recently, our group obtained a series of 2

Polyaminoazide mixtures for the synthesis of pH-responsive calixarene nanosponges

• Antonella Di Vincenzo,
• Antonio Palumbo Piccionello,
• Alberto Spinella,
• Delia Chillura Martino,
• Marco Russo and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2019, 15, 633–641, doi:10.3762/bjoc.15.59

• azide stretching of the reticulating agent, respectively. On the other hand, a tiny signal at 3140 cm−1 appears, which can be attributed to the Csp2–H stretching typical of the newly formed 1,2,3-triazole ring. The occurrence of the triazole ring is also accounted for by tiny signals at 1244, 1204, 1050

• NMR spectra (Figure 3) it is possible to recognize the peculiar cluster of four signals in the C-aromatic region, centered at ca. 127, 134, 146 and 154 ppm, due to the aromatic C atoms of the calixarene and triazole units. On the other hand, the aliphatic region shows a main signal centered at ca. 32

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

• heterocycles, which were additionally extended by triazole moieties, the compounds with electron-donating groups showed intramolecular charge transfer character (ICT/TICT) of the excited states which was proved by solvatochromic dynamics and supported by DFT calculations. In the 7-deazapurine series this led

• towards 2-amino-6-triazolylpurine derivatives was performed in a more atom economic way. The latter synthesis does not require a double cycloaddition followed by replacement of one of the triazole moieties. The final structural proof for the compounds of the series 7a–f and 8a–f was obtained by spectral

• comparison between compound 8a and regioisomeric compound 5. The 1H NMR comparison showed two main differences in the spectra (Figure 3): 1) the H–C(triazole) signal of product 8a is shifted downfield from 8.69 to 9.10 ppm and 2) the appearance of a CH2 signal near the N atom is changed from multiplet at

Olefin metathesis in multiblock copolymer synthesis

• Maria L. Gringolts,
• Yulia I. Denisova,
• Eugene Sh. Finkelshtein and
• Yaroslav V. Kudryavtsev

Beilstein J. Org. Chem. 2019, 15, 218–235, doi:10.3762/bjoc.15.21

• multiple click reactions of the diazido-telechelic PBD with a dialkynyl-containing azobenzene chromophore. The newly formed triazole moieties can tune and improve the photoresponsive properties of PBD. α,ω-Functional telechelic polymers also can be synthesized by acyclic diene metathesis (ADMET

Thermophilic phosphoribosyltransferases Thermus thermophilus HB27 in nucleotide synthesis

• Ilja V. Fateev,
• Ekaterina V. Sinitsina,
• Aiguzel U. Bikanasova,
• Maria A. Kostromina,
• Elena S. Tuzova,
• Larisa V. Esipova,
• Tatiana I. Muravyova,
• Alexei L. Kayushin,
• Irina D. Konstantinova and
• Roman S. Esipov

Beilstein J. Org. Chem. 2018, 14, 3098–3105, doi:10.3762/bjoc.14.289

• APRT limits the number of possible nucleotides that can be synthesized. Thus, for Thermus thermophilus HB27 APRT (TthAPRT), nucleotide synthesis is limited to the closest structural homologs of adenine (Table 1) [1]. Unfortunately, 1,2,4-triazole-3-carboxamide, its analogues, guanine, hypoxanthine, and

• phosphoribosyltransferase only [2]. Unfortunately, we did not find any product in reactions with compounds based on 1,2,4-triazole-3-carboxamide, which was also observed for E. сoli HPRT [15][16]. However, allopurinol and 8-azaguanine are substrates for TthHPRT, and 2-chloroadenine is a substrate for TthAPRT. For 2

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

• available lauroyl peroxide (2a), and TMSN3 (Table 1). In a preliminary experiment, the reaction of 1a with 2a in the presence of 10 mol % of CuCl in THF at 50 °C afforded 1,4-disubstituted 1,2,3-triazole 3a in 65% isolated yield (Table 1, entry 1). Surprisingly, under these conditions no CuAAC product

• , and 3ll). Remarkably, the chlorodiacyl peroxide also tolerated the reaction conditions to afford chloro-substituted triazole 3ee with good yield. Moreover, alkyl diacyl peroxides bearing a phenyl group, cyclopentyl group, or a cyclohexyl group also afforded good yields (3cc, 3mm, and 3nn

Photocatalyic Appel reaction enabled by copper-based complexes in continuous flow

• Clémentine Minozzi,
• Jean-Christophe Grenier-Petel,
• Shawn Parisien-Collette and
• Shawn K. Collins

Beilstein J. Org. Chem. 2018, 14, 2730–2736, doi:10.3762/bjoc.14.251

• complexes were poor catalysts, while when considering the diamine ligands the dq and bathophenthroline catalysts provided poor to modest yields. Also, BINAP and Xantphos-based catalysts tended to afford higher yields of 2, while amongst the diamines, the triazole-based complexes were almost all efficient at