Efficient syntheses of climate relevant isoprene nitrates and (1R,5S)-(−)-myrtenol nitrate

• Sean P. Bew,
• Glyn D. Hiatt-Gipson,
• Graham P. Mills and
• Claire E. Reeves

Beilstein J. Org. Chem. 2016, 12, 1081–1095, doi:10.3762/bjoc.12.103

• )propan-2-one (63) was easily generated via a two-step protocol (overall 63% yield) that started with the etherification of sodium para-methoxybenzyl alcolate with propargyl bromide [50]. The terminal alkyne on 62 was efficiently transformed into a ketone via an oxymercuration reaction using a combination

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

• the terminal alkyne 18 (97%). Magnesiation (iPrMgCl, THF) and reaction with ketone 6 afforded the benzyloxy-substituted bisindole 21. Transition metal-catalyzed Meyer–Schuster rearrangement afforded 24 (56%, E/Z mixture as above) albeit the catalyst loading had to be increased from 1 to 10 mol %, when

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

• terminal alkyne to the enamine simultaneously generates the copper acetylide and iminium ion, which are proposed to both bind to the chiral copper catalyst (see 4). A broad scope in the acetylene was observed, with arylalkynes resulting in the highest ee’s. To our knowledge, these were the first

Exploring architectures displaying multimeric presentations of a trihydroxypiperidine iminosugar

• Camilla Matassini,
• Stefania Mirabella,
• Andrea Goti,
• Inmaculada Robina,
• Antonio J. Moreno-Vargas and
• Francesca Cardona

Beilstein J. Org. Chem. 2015, 11, 2631–2640, doi:10.3762/bjoc.11.282

• chemistry approach involving the copper azide-alkyne-catalyzed cycloaddition (CuAAC) between suitable scaffolds bearing terminal alkyne moieties and an azido-functionalized piperidine as the bioactive moiety. A preliminary biological investigation is also reported towards commercially available and human

• synthesis of two different scaffolds bearing terminal alkyne moieties suitable for conjugation to compound 4. A preliminary evaluation of the role of the valency in enhancing the inhibitory activity of the iminosugar was investigated by synthesizing a tetravalent and a nonavalent scaffold. The tetravalent

Synthesis of bi- and bis-1,2,3-triazoles by copper-catalyzed Huisgen cycloaddition: A family of valuable products by click chemistry

• Zhan-Jiang Zheng,
• Ding Wang,
• Zheng Xu and
• Li-Wen Xu

Beilstein J. Org. Chem. 2015, 11, 2557–2576, doi:10.3762/bjoc.11.276

• azide, leading to the corresponding bistriazoles. In 2006, Aucagne and Leigh reported the synthesis of the TMS-alkyne and terminal-alkyne bis-functionalized tripeptide [28]. Here they used the CuAAC reaction of the terminal-alkyne-containing tripeptide 25 with the azide-containing dipeptide 26 in t-BuOH

• /H2O, catalyzed by CuSO4/sodium ascorbate, providing the first triazole-bearing intermediate (Scheme 11). They then performed the Ag(I)-catalyzed deprotection of the TMS-protected alkyne moiety, followed by another CuAAC reaction of the unmasked terminal alkyne with the second azide, giving the desired

• 33 in good yield. Then the nonactivated terminal alkyne reacts with another azide, catalyzed by an Amberlyst A-21/CuI system in CH2Cl2 to form the second triazole ring with high yield (Scheme 13). In this work, the authors further extended this method to the propiolamide, which was derived from meta

Easy access to heterobimetallic complexes for medical imaging applications via microwave-enhanced cycloaddition

• Nicolas Desbois,
• Sandrine Pacquelet,
• Adrien Dubois,
• Clément Michelin and
• Claude P. Gros

Beilstein J. Org. Chem. 2015, 11, 2202–2208, doi:10.3762/bjoc.11.239

• commercially available propargylamido-DOTA-tris(t-Bu)ester [29]. Complexation of 3 with a lanthanide was previously described by Borbas et al. [30]. Gd(DOTA) complex 10a, containing a pendant terminal alkyne group, was prepared by variation of a known procedure [29][31], as shown in Scheme 3. The complex was

Asymmetric 1,4-bis(ethynyl)bicyclo[2.2.2]octane rotators via monocarbinol functionalization. Ready access to polyrotors

• Cyprien Lemouchi and
• Patrick Batail

Beilstein J. Org. Chem. 2015, 11, 1881–1885, doi:10.3762/bjoc.11.202

• variety of functionalization sequences of BCO rotators by performing nucleophilic reactions on the terminal alkyne [16] as well as Sonogashira coupling reactions [17]. One way to synthesize 1 is via a catalytic reaction to achieve the deprotection of a single 2-methyl-3-butyn-2-ol and transform the

Preparation of conjugated dienoates with Bestmann ylide: Towards the synthesis of zampanolide and dactylolide using a facile linchpin approach

• Jingjing Wang,
• Samuel Z. Y. Ting and
• Joanne E. Harvey

Beilstein J. Org. Chem. 2015, 11, 1815–1822, doi:10.3762/bjoc.11.197

• 5b and 5c, respectively. While the reaction of 7b with aldehyde 8 in THF took 11 h to go to completion (62% isolated yield of 5b), the equivalent reaction in toluene required only 5 h (68% yield). Alcohol 7c was used to assess the compatibility of an unprotected, terminal alkyne in this linchpin

Synthesis of alpha-tetrasubstituted triazoles by copper-catalyzed silyl deprotection/azide cycloaddition

• Zachary L. Palchak,
• Paula T. Nguyen and
• Catharine H. Larsen

Beilstein J. Org. Chem. 2015, 11, 1425–1433, doi:10.3762/bjoc.11.154

• introduce a wide variety of substituents on 1,4-disubstituted 1,2,3-triazoles from the organic azide or terminal alkyne starting materials [1][2]. These Huisgen reactions [13] facilitate rapid drug screening by allowing for tracking in biological systems and the exploration of structure-activity

• relationships [10][14][15][16][17][18][19]. Propargylamines are a popular choice for the terminal alkyne component and form highly selective inhibitors (Figure 1) [2]. Due to the difficulty of forming tetrasubstituted propargylamines, the incorporation of deprotectable variants into triazoles is extremely rare

• assess whether conditions developed for in situ silyl deprotection would otherwise affect the azide when reacting with a simpler terminal alkyne (Scheme 2). As the copper-catalyzed cycloaddition of tert-butylacetylene and benzyl azide proceeds in 92% yield, decomposition of the benzyl azide or non-silyl

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• bromide gave the enyne product 166 (92%), which on further acylation of terminal alkyne with butanoyl chloride delivered compound 167 (82%). Then, it was subjected to an enyne metathesis with simple platinum salts such as PtCl2 and PtCl4 to give product 168 (79%). A subsequent reduction of the α,β

Single-molecule conductance of a chemically modified, π-extended tetrathiafulvalene and its charge-transfer complex with F₄TCNQ

• Raúl García,
• M. Ángeles Herranz,
• Edmund Leary,
• M. Teresa González,
• Gabino Rubio Bollinger,
• Marius Bürkle,
• Linda A. Zotti,
• Yoshihiro Asai,
• Fabian Pauly,
• Juan Carlos Cuevas,
• Nicolás Agraït and
• Nazario Martín

Beilstein J. Org. Chem. 2015, 11, 1068–1078, doi:10.3762/bjoc.11.120

• ), CuI, DIPEA) with trimethylsilylacetylene affords the symmetrically substituted exTTF 2 in good yield. Further removal of the trimethylsilyl group is easily achieved by treatment with potassium carbonate, yielding the free terminal alkyne 3 in quantitative yield. The introduction of the two anchor

Self-assembly of heteroleptic dinuclear metallosupramolecular kites from multivalent ligands via social self-sorting

• Christian Benkhäuser and
• Arne Lützen

Beilstein J. Org. Chem. 2015, 11, 693–700, doi:10.3762/bjoc.11.79

• (trimethylsilyl)acetylene into 7 in a yield of 85% [27]. Alkyne 7 was then subjected to a Negishi reaction with 2-bromopyridine (8) derived zinc organyl 9 to give the silyl-protected ethynylated bipyridine 10 in excellent yield of 99% which was subsequently desilylated under standard conditions to give terminal

• alkyne 11 in 96% yield [28]. Finally, a two-fold Sonogashira reaction with 1,3-diiodobenzene afforded the desired bis(2,2’-bipyridine) ligand 2 in quantitative yield. Metal coordination After the successful synthesis we prepared a DMSO solution of copper(I) ions, added it to the ligands (rac)-1 and 2

Design, synthesis and photochemical properties of the first examples of iminosugar clusters based on fluorescent cores

• Mathieu L. Lepage,
• Antoine Mirloup,
• Manon Ripoll,
• Fabien Stauffert,
• Anne Bodlenner,
• Raymond Ziessel and
• Philippe Compain

Beilstein J. Org. Chem. 2015, 11, 659–667, doi:10.3762/bjoc.11.74

• carefully degassed conditions and the desired protected cluster 12b could be obtained in 56% yield after purification on silica gel (Scheme 2). The major side-product observed which could not be isolated in pure form may correspond to CuAAC reaction of the azido iminosugar 4a with the terminal alkyne

Direct access to pyrido/pyrrolo[2,1-b]quinazolin-9(1H)-ones through silver-mediated intramolecular alkyne hydroamination reactions

• Hengshuai Wang,
• Shengchao Jiao,
• Kerong Chen,
• Xu Zhang,
• Linxiang Zhao,
• Dan Liu,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2015, 11, 416–424, doi:10.3762/bjoc.11.47

• activation of the terminal alkyne moiety of the substrate with AgOTf to generate the Ag–alkyne π complex I (or its tautomer II). Subsequently, the Ag–alkyne π complex I or II is converted into complex III through a nucleophilic attack of the nitrogen atom of the amide, and then produces the final product

Formation of nanoparticles by cooperative inclusion between (S)-camptothecin-modified dextrans and β-cyclodextrin polymers

• Thorbjørn Terndrup Nielsen,
• Catherine Amiel,
• Laurent Duroux,
• Kim Lambertsen Larsen,
• Lars Wagner Städe,
• Reinhard Wimmer and
• Véronique Wintgens

Beilstein J. Org. Chem. 2015, 11, 147–154, doi:10.3762/bjoc.11.14

• (I) compared to alkynes, stabilized with TBTA (Scheme 2). In order to maintain a reductive environment 15 mol % sodium ascorbate was added. The “click” conjugation was achieved within 24 hours at ambient temperature. The complete conversion of terminal alkyne protons with corresponding appearance of

Articulated rods – a novel class of molecular rods based on oligospiroketals (OSK)

• Pablo Wessig,
• Roswitha Merkel and
• Peter Müller

Beilstein J. Org. Chem. 2015, 11, 74–84, doi:10.3762/bjoc.11.11

• defined a 1,2,3-triazole containing linkage between two piperidine rings as the flexible joint F, which should be easily accessible by copper-catalyzed cycloaddition between an azide G and a terminal alkyne H (CuAAC, “Click” reaction) [16]. Primary alcohols I serve as “protected” azides accessible by

• , the PMB group was cleaved by DDQ to give the orthogonally protected trispiro rod 8 (Scheme 1). To demonstrate the capability of the approach outlined in Figure 3 we selectively activated both sides of building block 8 either by introduction of an azide group (9) or liberation of the terminal alkyne by

Synthesis of antibacterial 1,3-diyne-linked peptoids from an Ugi-4CR/Glaser coupling approach

• Martin C. N. Brauer,
• Ricardo A. W. Neves Filho,
• Bernhard Westermann,
• Ramona Heinke and
• Ludger A. Wessjohann

Beilstein J. Org. Chem. 2015, 11, 25–30, doi:10.3762/bjoc.11.4

• were obtained in good yields. The next step was the copper-catalysed homocoupling (Glaser reaction) of the terminal alkyne functions. Albeit several protocols are reported for this reaction, the CuCl-catalyzed method recently described by Jia and co-workers was utilised to access the C2-symmetric 1,3

Sequential decarboxylative azide–alkyne cycloaddition and dehydrogenative coupling reactions: one-pot synthesis of polycyclic fused triazoles

• Kuppusamy Bharathimohan,
• Thanasekaran Ponpandian,
• A. Jafar Ahamed and
• Nattamai Bhuvanesh

Beilstein J. Org. Chem. 2014, 10, 3031–3037, doi:10.3762/bjoc.10.321

• cycloaddition, CuAAC) between an organic azide and a terminal alkyne is a well-established strategy for the construction of 1,4-disubstituted 1,2,3-triazoles [1][2][3][4]. In a recent development, this decarboxylative coupling reaction was well documented for the generation of C–C bonds [5]. This method has

A general metal-free approach for the stereoselective synthesis of C-glycals from unactivated alkynes

• Shekaraiah Devari,
• Manjeet Kumar,
• Ramesh Deshidi,
• Masood Rizvi and
• Bhahwal Ali Shah

Beilstein J. Org. Chem. 2014, 10, 2649–2653, doi:10.3762/bjoc.10.277

• challenge. We reasoned that the development of a strategy which in situ activates the terminal alkyne and further catalyzes the reaction without the aid of other Lewis acids might be a solution to this problem. Thus, in continuation of our efforts [36][37][38], we describe a highly stereoselective TMSOTf

A small azide-modified thiazole-based reporter molecule for fluorescence and mass spectrometric detection

• Stefanie Wolfram,
• Hendryk Würfel,
• Stefanie H. Habenicht,
• Christine Lembke,
• Phillipp Richter,
• Eckhard Birckner,
• Rainer Beckert and
• Georg Pohnert

Beilstein J. Org. Chem. 2014, 10, 2470–2479, doi:10.3762/bjoc.10.258

• , fluorescent and MS techniques. Conclusion We introduce the azide-modified thiazole-based reporter molecule BPT (1) with superior properties for fluorescence, UV and MS detection compared to other common reporters. BPT (1) can be easily synthesized and attached to terminal alkyne-modified molecules via CuAAC

Synthesis and solvodynamic diameter measurements of closely related mannodendrimers for the study of multivalent carbohydrate–protein interactions

• Yoann M. Chabre,
• Alex Papadopoulos,
• Alexandre A. Arnold and
• René Roy

Beilstein J. Org. Chem. 2014, 10, 1524–1535, doi:10.3762/bjoc.10.157

• (18H), and the terminal alkyne protons (9H) at δ 4.16, 3.87, and 2.48 ppm, respectively. Toward the last and further extended 9-mer 21, a convergent strategy was rather adopted (Scheme 4). This strategy has the clear advantages of providing an easier purification process from partially substituted end

An economical and safe procedure to synthesize 2-hydroxy-4-pentynoic acid: A precursor towards ‘clickable’ biodegradable polylactide

• Quanxuan Zhang,
• Hong Ren and
• Gregory L. Baker

Beilstein J. Org. Chem. 2014, 10, 1365–1371, doi:10.3762/bjoc.10.139

• with low cost. Malonate has a low pKa of ~13 and can be easily deprotonated and alkylated by mild bases such as sodium/potassium alkoxides without deprotonating a terminal alkyne. Conveniently, both malonate and propargyl alcohol are commercially available in bulk quantities. Herein, we report one

Preparation of phosphines through C–P bond formation

• Iris Wauters,
• Wouter Debrouwer and
• Christian V. Stevens

Beilstein J. Org. Chem. 2014, 10, 1064–1096, doi:10.3762/bjoc.10.106

Isocyanide-based multicomponent reactions towards cyclic constrained peptidomimetics

• Gijs Koopmanschap,
• Eelco Ruijter and
• Romano V.A. Orru

Beilstein J. Org. Chem. 2014, 10, 544–598, doi:10.3762/bjoc.10.50

Practical synthesis of aryl-2-methyl-3-butyn-2-ols from aryl bromides via conventional and decarboxylative copper-free Sonogashira coupling reactions

• Andrea Caporale,
• Stefano Tartaggia,
• Andrea Castellin and
• Ottorino De Lucchi

Beilstein J. Org. Chem. 2014, 10, 384–393, doi:10.3762/bjoc.10.36

• acetylene after reductive elimination. The activated acetylide species for the coupling process is generated from the reaction of a terminal alkyne with copper in the presence of a base and is transferred on the palladium site via transmetallation. In order to improve the efficacy of the reaction, several

• derived from the starting aryl bromides in a 2–5% yield range. Likely, the acetone protecting group is cleaved from protected terminal alkyne even under such mild conditions and therefore, the terminal alkyne generated in situ couples with another molecule of the starting aryl bromide to provide the