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

• activation of the N-benzamidomethyltetrazole core followed by isoquinolone-ring formation to furnish 4a. We endeavored two catalytic systems based on ruthenium and rhodium, which in our laboratory have proven success in this type of cyclization [32][48]. First, the alkynylation protocol was attempted using

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

One-pot activation–alkynylation–cyclization synthesis of 1,5-diacyl-5-hydroxypyrazolines in a consecutive three-component fashion

• Christina Görgen,
• Katharina Boden,
• Guido J. Reiss,
• Walter Frank and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 1360–1370, doi:10.3762/bjoc.15.136

• Chemie und Makromolekulare Chemie, Universitätsstraße 1, D-40225 Düsseldorf, Germany 10.3762/bjoc.15.136 Abstract A consecutive three-component activation–alkynylation–cyclization reaction of (hetero)aryl glyoxylic acids, oxalyl chloride, arylacetylenes, and hydrazides efficiently forms 1,5-diacyl-5

• -hydroxypyrazolines in moderate to good yields. The structures were unambiguously corroborated by comprehensive NMR spectroscopy and X-ray structure analyses of selected derivatives. Keywords: activation; alkynylation; C–C coupling; copper; cyclization; multicomponent reactions; Introduction Pyrazoles [1][2] and

• –alkynylation (GA) [48] and an activation–alkynylation (AA) [49] sequence, which both take advantage of a copper-catalyzed alkynylation of the intermediary formed (hetero)arylglyoxyl chloride (Scheme 1). The alkynediones can be subsequently transformed, still in the same reaction vessel, to quinoxalines [48][50

Synthesis of 2H-furo[2,3-c]pyrazole ring systems through silver(I) ion-mediated ring-closure reaction

• Vaida Milišiūnaitė,
• Rūta Paulavičiūtė,
• Eglė Arbačiauskienė,
• Vytas Martynaitis,
• Wolfgang Holzer and
• Algirdas Šačkus

Beilstein J. Org. Chem. 2019, 15, 679–684, doi:10.3762/bjoc.15.62

• alkynylation/cyclization reaction between 2-iodophenol and (triethoxysilyl)alkynes [20]. In recent years silver and gold salts have found application as versatile and mild catalysts to access the benzo[b]furan ring system through intramolecular cyclization of 2-alkynylphenol substrates [21], including

• construction of the 2H-furo[2,3-c]pyrazole ring system by a Sonogashira-type alkynylation of 4-iodopyrazol-3-ol and subsequent intramolecular 5-endo-dig cyclization of the obtained hydroxyalkynyl substrate mediated by a Ag(I) catalyst. Results and Discussion The synthetic strategy designed to construct the 2H

A novel and efficient synthesis of phenanthrene derivatives via palladium/norbornadiene-catalyzed domino one-pot reaction

• Yue Zhong,
• Wen-Yu Wu,
• Shao-Peng Yu,
• Tian-Yuan Fan,
• Hai-Tao Yu,
• Nian-Guang Li,
• Zhi-Hao Shi,
• Yu-Ping Tang and
• Jin-Ao Duan

Beilstein J. Org. Chem. 2019, 15, 291–298, doi:10.3762/bjoc.15.26

• alkynylation for the aryl iodides. In this paper, we developed an efficient domino reaction of aryl iodides with ortho-bromobenzoyl chlorides and norbornadiene leading to phenanthrene derivatives, which could be widely used in the synthesis of vital intermediates for functional materials, pharmaceutical agents

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

• introduced the Na2S2O8-promoted ring-opening/alkynylation of cyclopropanols 91 with ethynylbenziodoxolones (EBX) 116 for the synthesis of the alkynylated ketones 117 (Scheme 27) [107]. This reaction involved a C–C bond cleavage, radical rearrangement, and C–C bond formation, and showed a wide substrates

• 2016, the silver-promoted oxidative ring-opening/alkynylation of cyclopropanols 91 with ethynylbenziodoxolones (EBX) 116 had been presented by Li and co-workers (Scheme 29) [109]. Both silver(I) nitrate and potassium persulfate played an important role in this transformation. In 2016, Hu and co-workers

• trifluoromethylation/trifluoromethylthiolation of cyclopropanols. Ag(I)-mediated oxidative ring-opening/fluorination of cyclopropanols with Selectfluor. Photocatalyzed ring-opening/fluorination of cyclopropanols with Selectfluor. Na2S2O8-promoted ring-opening/alkynylation of cyclopropanols with EBX. Ag(I)-catalyzed

Stereoselective total synthesis and structural revision of the diacetylenic diol natural products strongylodiols H and I

• Pamarthi Gangadhar,
• Sayini Ramakrishna,
• Ponneri Venkateswarlu and
• Pabbaraja Srihari

Beilstein J. Org. Chem. 2018, 14, 2313–2320, doi:10.3762/bjoc.14.206

• concentrations [11]. There have been few contributions on the total synthesis of strongylodiols [12][13] employing alkynylation of an unsaturated aliphatic aldehyde catalyzed by Trost’s pro-phenol ligand [12][14], β-elimination of epoxy chloride [15], Noyori’s asymmetric reduction of ynones [16], diyne addition

Hypervalent organoiodine compounds: from reagents to valuable building blocks in synthesis

• Gwendal Grelier,
• Benjamin Darses and
• Philippe Dauban

Beilstein J. Org. Chem. 2018, 14, 1508–1528, doi:10.3762/bjoc.14.128

• efficiency of the reaction is limited by the need to use 2 equivalents of allenes 20 to obtain good yields. λ3-Iodane reagents: alkynylbenziodoxolone Ethynylbenziodoxolone (EBX) is a powerful reagent to perform the electrophilic alkynylation of various functional groups such as carbonyl derivatives, thiols

• benzoate motif and the alkynyl group are obtained from various acceptor or donor–acceptor diazo compounds 30, while the use of vinyldiazo derivatives 32 leads to enynes 33 arising from the vinylogous addition of the carboxylate. Significantly, the benzoyloxy-alkynylation reaction can be applied to the late

• involve the formation of the copper-carbene species 35, to which the carboxylate of alkynylbenziodoxolone could add to afford the intermediate 36. Final alkynyl transfer would give rise to the products 31 and 33, however, the nature of this alkynylation step remains to be elucidated. In a subsequent study

A survey of chiral hypervalent iodine reagents in asymmetric synthesis

• Soumen Ghosh,
• Suman Pradhan and
• Indranil Chatterjee

Beilstein J. Org. Chem. 2018, 14, 1244–1262, doi:10.3762/bjoc.14.107

• could be achieved even by using a 50 mol % catalyst loading. A nucleophilic attack of the fluoride ion to the intermediate 104 or a possible ligand coupling pathway via 105 could justify the product formation (Scheme 23). Waser et al. developed an asymmetric alkynylation of β-ketoesters and amides 107

• for the alkynylation of β-ketoesters [76]. Pouységu and Quideau et al. prepared new axially chiral biaryl I(III) reagents 18 assembled with alkynyl ligands. They were able to achieve alkynylation of β-ketoesters 114 as well as dearomative alkynylation of phenolic derivatives 118 to obtain derivatives

• oxylation of ketones reported by Masson et al. α-Fluorination of β-keto esters. Alkynylation of β-ketoesters and amides catalyzed by phase-transfer catalyst. Alkynylation of β-ketoesters and dearomative alkynylation of phenols. Acknowledgements The authors highly acknowledge the financial assistance

Investigations of alkynylbenziodoxole derivatives for radical alkynylations in photoredox catalysis

• Yue Pan,
• Kunfang Jia,
• Yali Chen and
• Yiyun Chen

Beilstein J. Org. Chem. 2018, 14, 1215–1221, doi:10.3762/bjoc.14.103

• Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China 10.3762/bjoc.14.103 Abstract The alkynylbenziodoxole derivatives are recently developed alkynylation reagents in organic synthesis, which demonstrate excellent radical alkynylation reactivity in photoredox

• catalysis reactions. Herein we report the synthesis of alkynylbenziodoxole derivatives with difluoro, monofluoro, monomethoxy, and dimethoxy substitution on the benziodoxole moiety, and investigated their radical alkynylation reactivity for the first time. A series of mechanistic experiments were conducted

• radical; alkynylbenziodoxoles; photoredox catalysis; radical alkynylation; Introduction The introduction of the alkynyl group to organic molecules is an important synthetic transformation in organic synthesis [1][2][3][4]. Recently, cyclic iodine(III) reagents (CIR)-substituted alkynes

Rhodium-catalyzed C–H functionalization of heteroarenes using indoleBX hypervalent iodine reagents

• Erwann Grenet,
• Ashis Das,
• Paola Caramenti and
• Jérôme Waser

Beilstein J. Org. Chem. 2018, 14, 1208–1214, doi:10.3762/bjoc.14.102

• nitrogen and a transition metal catalyst (reaction 1, Scheme 1A) [11][12][13][14][15][16][17][18][19]. In particular, Li and co-workers have used ethynylbenziodoxolone (EBX) hypervalent iodine reagents to achieve a regiodivergent alkynylation of the pyridinone core employing either a gold(I) or a rhodium

• these conditions to different quinoline N-oxides (Scheme 3). This class of substrates had also been used for C–H alkynylation using EBX reagents [28]. During our previous work, we had attempted the C8-heteroarylation of quinoline N-oxide with Me-indoleBX 6a. However, the transformation required a

Preparation, structure, and reactivity of bicyclic benziodazole: a new hypervalent iodine heterocycle

• Akira Yoshimura,
• Michael T. Shea,
• Cody L. Makitalo,
• Melissa E. Jarvi,
• Gregory T. Rohde,
• Akio Saito,
• Mekhman S. Yusubov and
• Viktor V. Zhdankin

Beilstein J. Org. Chem. 2018, 14, 1016–1020, doi:10.3762/bjoc.14.87

• efficient electrophilic atom-transfer reagents useful for conversion of various organic substrates to the corresponding products of azidation [7][8][9][10][11], amination [12][13], cyanation [14][15][16][17], alkynylation [18][19][20], or chlorination [21][22]. Recently, Zhang and co-workers reported the

Functionalization of N-arylglycine esters: electrocatalytic access to C–C bonds mediated by n-Bu₄NI

• Mi-Hai Luo,
• Yang-Ye Jiang,
• Kun Xu,
• Yong-Guo Liu,
• Bao-Guo Sun and
• Cheng-Chu Zeng

Beilstein J. Org. Chem. 2018, 14, 499–505, doi:10.3762/bjoc.14.35

• ]. Later on, arylation, vinylation and alkynylation of glycine derivatives were also accomplished by the same group (Scheme 1) [13]. Using the Cu(OAc)2/pyrrolidine dual catalysts system, Huang developed the oxidative cross coupling of glycine derivatives with acetone in the presence of TBHP or DDQ as

Mechanochemical synthesis of small organic molecules

• Tapas Kumar Achar,
• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186

• reaction under mechanomilling [67]. Asymmetric alkynylation of prochiral sp3 C–H bonds via CDC [68]. Fe(III)-catalyzed CDC coupling of 3-benzylindoles [69]. Mechanochemical synthesis of 3-vinylindoles and β,β-diindolylpropionates [70]. Mechanochemical C–N bond construction using anilines and arylboronic

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

Effect of uridine protecting groups on the diastereoselectivity of uridine-derived aldehyde 5’-alkynylation

• Raja Ben Othman,
• Mickaël J. Fer,
• Laurent Le Corre,
• Sandrine Calvet-Vitale and
• Christine Gravier-Pelletier

Beilstein J. Org. Chem. 2017, 13, 1533–1541, doi:10.3762/bjoc.13.153

• -Paris), 45 rue des Saints Pères, 75270 Paris 06, France 10.3762/bjoc.13.153 Abstract The 5’-alkynylation of uridine-derived aldehydes is described. The addition of alkynyl Grignard reagents on the carbonyl group is significantly influenced by the 2’,3’-di-O-protecting groups (R1): O-alkyl groups led to

• modest diastereoselectivities (65:35) in favor of the 5’R-isomer, whereas O-silyl groups promoted higher diastereoselectivities (up to 99:1) in favor of the 5’S-isomer. A study related to this protecting group effect on the diastereoselectivity is reported. Keywords: diastereoselective alkynylation

• ratio (Table 2, entry 15). The three attempts of C-5’ alkynylation of N-3-allylated uridine aldehydes, did not revealed marked influence on the diastereoselective ratio (Table 2, entries 3, 8, 15). To explain the diastereoselective outcome of the reaction, we first considered Cram chelated models

Synthesis of alkynyl-substituted camphor derivatives and their use in the preparation of paclitaxel-related compounds

• M. Fernanda N. N. Carvalho,
• Rudolf Herrmann and
• Gabriele Wagner

Beilstein J. Org. Chem. 2017, 13, 1230–1238, doi:10.3762/bjoc.13.122

• framework and the alkynyl substituent come at relatively similar values and do not allow distinguishing between 12 and 13 reliably. In view of the above results, it was clear that a more selective method was needed that generally allows for mono-alkynylation and for differentiation between the carbonyl

Transition-metal-free one-pot synthesis of alkynyl selenides from terminal alkynes under aerobic and sustainable conditions

• Adrián A. Heredia and
• Alicia B. Peñéñory

Beilstein J. Org. Chem. 2017, 13, 910–918, doi:10.3762/bjoc.13.92

• , respectively). This result shows that under the conditions used, the Ph2Se2 addition reaction to the triple bond competes with Se-alkynylation. This side reaction is less efficient when the concentration decreases, favoring the reaction of interest when the amount of solvent increases. Subsequently, a set of

Nucleophilic and electrophilic cyclization of N-alkyne-substituted pyrrole derivatives: Synthesis of pyrrolopyrazinone, pyrrolotriazinone, and pyrrolooxazinone moieties

• Işıl Yenice,
• Sinan Basceken and
• Metin Balci

Beilstein J. Org. Chem. 2017, 13, 825–834, doi:10.3762/bjoc.13.83

• N-alkyne-substituted pyrrole derivatives 7a–d. A practical method is the coupling reaction of substituted pyrroles with alkynyl bromides using catalytic CuSO4·5H2O and 1,10-phenanthroline [31]. When alkynylation with 11a was carried out at 85 °C, the conversion was only 12%. We assume this is due to

Synthesis of ribavirin 2’-Me-C-nucleoside analogues

• Fanny Cosson,
• Aline Faroux,
• Jean-Pierre Baltaze,
• Jonathan Farjon,
• Régis Guillot,
• Jacques Uziel and
• Nadège Lubin-Germain

Beilstein J. Org. Chem. 2017, 13, 755–761, doi:10.3762/bjoc.13.74

• carbon atom in the 2’-position are an indium-mediated alkynylation and a 1,3-dipolar cyclization. Keywords: alkynylation; antiviral; cancer; C-nucleosides; ribavirin; Introduction The triazole nucleoside ribavirin (RBV, Figure 1) is used for the treatment of a number of viral infections and may be

• of antivirals due to their stability in biological fluids and their bioavailability. Some years ago, we described an approach leading to the C-ribosylated analogue 1 of ribavirin (Figure 2) with the key-steps of the synthesis being an indium-mediated alkynylation of a ribose derivative followed by

• commercially available 2-C-methyl-1,2,3,5-tetra-O-benzoyl-β-D-ribofuranose (4) as shown in Scheme 1. Debenzoylation of 4 followed by selective protection led to derivative 5, which was submitted to the indium-mediated alkynylation reaction affording the alkynyl riboside 6 with the same β-anomeric selectivity

Effect of the ortho-hydroxy group of salicylaldehyde in the A³ coupling reaction: A metal-catalyst-free synthesis of propargylamine

• Sujit Ghosh,
• Kinkar Biswas,
• Suchandra Bhattacharya,
• Pranab Ghosh and
• Basudeb Basu

Beilstein J. Org. Chem. 2017, 13, 552–557, doi:10.3762/bjoc.13.53

• ], mercury [26], cobalt [27], iridium [28], ruthenium [29], indium [30] etc. Other methods towards the synthesis of propargylamine include: alkynylation of imine [31][32][33], enamine [34], and Csp³–H bonds adjacent to N-atoms [35][36]. In the A3 coupling, the role of the metal catalyst is believed to

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98

• state for the observed stereoselectivity. Pyrrole attacked the ketone from the Si face to generate (R)-3-pyrrolyl-3-hydroxyoxindoles. Very recently, Feng et al. revealed that the bifunctional guanidine (L3)/CuI catalyst can catalyze asymmetric alkynylation of isatins with terminal alkynes, affording

Gold-catalyzed direct alkynylation of tryptophan in peptides using TIPS-EBX

• Gergely L. Tolnai,
• Jonathan P. Brand and
• Jerome Waser

Beilstein J. Org. Chem. 2016, 12, 745–749, doi:10.3762/bjoc.12.74

• is highly attractive, but the use of a carbon linker is usually required. Herein, we report the gold-catalyzed direct alkynylation of tryptophan in peptides using the hypervalent iodine reagent TIPS-EBX (1-[(triisopropylsilyl)ethynyl]-1,2-benziodoxol-3(1H)-one). The reaction proceeded in 50–78% yield

• using a linker is used, for example an alkylation reaction of cysteine. The direct introduction of an alkyne onto the biomolecule would be interesting to profit from modified electronic and spectroscopic properties. However, the direct alkynylation of peptides or proteins is usually based on the use of

• the Sonogashira reaction, which requires modified non-natural amino acids [32][33]. In 2013, our group reported the alkynylation of thiols using the hypervalent iodine reagent TIPS-EBX (1a, 1-[(triisopropylsilyl)ethynyl]-1,2-benziodoxol-3(1H)-one) (Scheme 1A) [34]. The reaction was almost

Study on the synthesis of the cyclopenta[f]indole core of raputindole A

• Nils Marsch,
• Mario Kock and
• Thomas Lindel

Beilstein J. Org. Chem. 2016, 12, 334–342, doi:10.3762/bjoc.12.36

• PMB group, because the oxidation potential of DMB ethers is lower and the cleavage was expected to be more facile [45]. Indole synthesis from DMB-protected 13 and subsequent Boc protection afforded 16 (58%). Alkynylation and desilylation of 16 to 19 and coupling of 19 with ketone 6 proceeded smoothly

Enantioselective additions of copper acetylides to cyclic iminium and oxocarbenium ions

• Jixin Liu,
• Srimoyee Dasgupta and
• Mary P. Watson

Beilstein J. Org. Chem. 2015, 11, 2696–2706, doi:10.3762/bjoc.11.290

• -based catalysts [9][10][11][12][13][14][15]. Among these, chiral copper catalysts have been used with remarkable success in the alkynylation of cyclic iminium ion and oxocarbenium ion intermediates. This review will focus on the development of these enantioselective, copper-catalyzed alkynylations

• , this reaction can be carried out in H2O, as well as PhMe. Nearly simultaneously, Knochel’s group reported an enantioselective CuBr/Quinap-catalyzed alkynylation to deliver propargylic amines with alkyl substitution at the stereocenter (Scheme 2) [18][19][20]. In this reaction, proton transfer from the

• for enantioselective alkynylations of cyclic electrophiles. The first enantioselective, copper-catalyzed alkynylation of a cyclic iminium ion was reported by Li’s research group in 2004 [22]. Building on their development of a cross-dehydrogenative coupling (CDC) reaction between benzylic amines and