Multicomponent syntheses of pyrazoles via (3 + 2)-cyclocondensation and (3 + 2)-cycloaddition key steps

• Ignaz Betcke,
• Alissa C. Götzinger,
• Maryna M. Kornet and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2024, 20, 2024–2077, doi:10.3762/bjoc.20.178

Active-metal template clipping synthesis of novel [2]rotaxanes

• Cătălin C. Anghel,
• Teodor A. Cucuiet,
• Niculina D. Hădade and
• Ion Grosu

Beilstein J. Org. Chem. 2023, 19, 1776–1784, doi:10.3762/bjoc.19.130

• the reaction used to complete rotaxane synthesis, hence the name “active template”. This strategy was first applied by Saito and co-workers [35], using a Cu(I) template to catalyze a Glaser coupling reaction. The method has been extended for other reactions, for example Ni-catalyzed homocoupling of

1,2,3-Triazoles as leaving groups in S_NAr–Arbuzov reactions: synthesis of C6-phosphonated purine derivatives

• Kārlis-Ēriks Kriķis,
• Irina Novosjolova,
• Anatoly Mishnev and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 193–202, doi:10.3762/bjoc.17.19

• solutions, as used in the Cu(II) and ascorbate protocol. In some cases, the use of Et3N lowered the yield of 2,6-bistriazolylpurines 6c and 6f–i due to the competing Glaser coupling [38][39] and the reduction of 2,6-diazide 5 by the Cu(I) species [40][41]. The bistriazolyl derivatives 6a–i were easily

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

• connected asymmetric bowls, as well as atropisomerism, was constructed by Hirao and his two group members, namely Amaya and Kobayashi, starting from the same bromo derivative 82. First it was converted into ethynylsumanene 91 using a Sonogashira-coupling which on subsequent desilylation and Glaser-coupling

Towards triptycene functionalization and triptycene-linked porphyrin arrays

• Gemma M. Locke,
• Keith J. Flanagan and
• Mathias O. Senge

Beilstein J. Org. Chem. 2020, 16, 763–777, doi:10.3762/bjoc.16.70

• with porphyrin 8 [40], resulting in a yield of 50% of the purple-green product 9. An additional reaction was carried out via a Glaser coupling with BODIPY 10 in order to extend the distance between the two BODIPY chromophores but the desired product 11 could not be detected by spectroscopic techniques

Regioselectively α- and β-alkynylated BODIPY dyes via gold(I)-catalyzed direct C–H functionalization and their photophysical properties

• Takahide Shimada,
• Shigeki Mori,
• Masatoshi Ishida and
• Hiroyuki Furuta

Beilstein J. Org. Chem. 2020, 16, 587–595, doi:10.3762/bjoc.16.53

• Glaser-coupling reactions [37]. Conventionally, an alkynylation of the BODIPY core has been achieved by palladium-catalyzed Sonogashira cross-coupling with halogenated BODIPYs (Figure 1b) [35][37]. However, due to the coexistence of multiple C–H bonds, a regioselective direct C–H alkynylation of the

Nanopatterns of arylene–alkynylene squares on graphite: self-sorting and intercalation

• Tristan J. Keller,
• Joshua Bahr,
• Kristin Gratzfeld,
• Nina Schönfelder,
• Marcin A. Majewski,
• Marcin Stępień,
• Sigurd Höger and
• Stefan-S. Jester

Beilstein J. Org. Chem. 2019, 15, 1848–1855, doi:10.3762/bjoc.15.180

• other sides of the square is based on the Glaser coupling of acetylene-terminated precursor structures. These side chains give macrocycles with reduced symmetry. They cannot be obtained by the cyclization of small building blocks, but require the stepwise formation of more complex precursors, where the

Interactions between shape-persistent macromolecules as probed by AFM

• Johanna Blass,
• Jessica Brunke,
• Franziska Emmerich,
• Cédric Przybylski,
• Vasil M. Garamus,
• Artem Feoktystov,
• Roland Bennewitz,
• Gerhard Wenz and
• Marcel Albrecht

Beilstein J. Org. Chem. 2017, 13, 938–951, doi:10.3762/bjoc.13.95

• end groups were prepared starting from diacetylene-modified cyclodextrin monomers by a combined Glaser coupling/click chemistry approach. Structural perfection of the neutral CD polymers and inclusion complex formation with ditopic and monotopic guest molecules were proven by MALDI–TOF and UV–vis

• phenyl moieties and β-CD rings leading to daisy chains [54]. The polymerization of 7 was performed through Glaser coupling in pyridine catalyzed by Cu(I)/Cu(II). After removal of low molecular weight material by ultrafiltration polymer 8 was isolated as a light orange solid in 91% yield. Polyrotaxane

• than one polymer molecule might be involved. Conclusion In conclusion, regular water-soluble shape-persistent CD polymers based on poly(phenylene butadiynylene) were prepared by a straightforward Glaser coupling/click chemistry approach, which can be attached to planar silicon surfaces as well as AFM

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

• possibility for the Glaser coupling of the terminal alkyne as the byproduct [37]. Interestingly, hitherto there is no report for the A3 coupling reaction in the absence of a metal catalyst except of one example in a three-component reaction using an alkynylcarboxylic acid instead of a terminal alkyne [38]. In

• are straightforward and products are obtained in good to excellent yields. The metal-free approach also offers the advantages of avoiding any possible byproduct arising out from the Glaser coupling of terminal alkynes as well as contamination with metal species. The present protocol supersedes the

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

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

• linking reactions like, e.g., click reactions or amide bonds, the Glaser coupling allows the use of truly identical monomers. This decreases the number of steps for appropriate starting materials, and allows access to true homodimers in sensu strictu. Results and Discussion To achieve the synthesis of

• monomers eligible for dimerizations by Glaser coupling, equimolar amounts of propargylamine (3), aldehyde 4, carboxylic acid 5, and isocyanides 6 were reacted in methanol at room temperature over 24 h following well established Ugi protocols [12]. After flash column chromatography N-propargyl peptoids 7a–j

• . In addition, HPLC analyses revealed that an adjacent stereocenter (Table 1, entry 8, 7h/8h) does not racemize under the reaction conditions of both the MCR and the Glaser coupling. Due to the high selectivity and high conversions found in the Glaser coupling step, our attention turned toward the

Building complex carbon skeletons with ethynyl[2.2]paracyclophanes

• Ina Dix,
• Lidija Bondarenko,
• Peter G. Jones,
• Thomas Oeser and
• Henning Hopf

Beilstein J. Org. Chem. 2014, 10, 2013–2020, doi:10.3762/bjoc.10.209

• , highly unsaturated carbon frameworks. Thus both the pseudo-geminal- 2 and the pseudo-ortho-diethynylcyclophane 4 can be dimerized by Glaser coupling to the respective dimers 9/10 and 11/12. Whereas the former isomer pair could not be separated so far, the latter provided the pure diastereomers after

• their usual spectroscopic and analytical data, the new cyclophanes 11, 12, 19, 20, 22, and 26 were characterized by X-ray structural analysis. Keywords: carbon-rich molecules; complex carbon scaffolds; cyclophanes; Glaser coupling; multibridged cyclophanes; X-ray analysis; Introduction Several years

• - (1), 1,3- (3), and 1,4-diethynylbenzene (5) (Scheme 1). These simple, flat molecules have been used extensively for the deliberate construction of larger polyaromatic hydrocarbons employing classical (e.g., Glaser coupling and its variants) or modern acetylenic coupling reactions (e.g., the

The influence of intraannular templates on the liquid crystallinity of shape-persistent macrocycles

• Joscha Vollmeyer,
• Ute Baumeister and
• Sigurd Höger

Beilstein J. Org. Chem. 2014, 10, 910–920, doi:10.3762/bjoc.10.89

• 4, 06120 Halle (Saale), Germany 10.3762/bjoc.10.89 Abstract A series of shape-persistent phenylene–ethynylene–naphthylene–butadiynylene macrocycles with different extraannular alkyl groups and intraannular bridges is synthesized by oxidative Glaser-coupling of the appropriate precursors. The

• longer intraannular alkyl bridge of 1b prevents a close packing of the rings and leads in this case even to the absence of the lc phase. Conclusion In summary, shape-persistent macrocycles with intraannular bridges were synthesized by oxidative Glaser-coupling of the appropriate acetylenes. The bridges

Rapid pseudo five-component synthesis of intensively blue luminescent 2,5-di(hetero)arylfurans via a Sonogashira–Glaser cyclization sequence

• Fabian Klukas,
• Alexander Grunwald,
• Franziska Menschel and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2014, 10, 672–679, doi:10.3762/bjoc.10.60

• in a pseudo five-component reaction via a Sonogashira–Glaser coupling sequence followed by a superbase-mediated (KOH/DMSO) cyclization in a consecutive one-pot fashion. Besides the straightforward synthesis of natural products and biologically active molecules all representatives are particularly

Advancements in the mechanistic understanding of the copper-catalyzed azide–alkyne cycloaddition

• Regina Berg and
• Bernd F. Straub

Beilstein J. Org. Chem. 2013, 9, 2715–2750, doi:10.3762/bjoc.9.308

• with quantitative conversion to give the 1,4-disubstituted 1,2,3-triazole exclusively. Common side reactions such as the Glaser coupling [9][10][11] are not observed. The presented reaction conditions are compatible with a variety of functional groups such as ester, ether, amide, thioether, Fmoc and

• (I) oxidation state in aqueous solution [14][64]. This is important as Cu(II) ions are harmful to this experiment in two ways: on the one hand, Cu(II) ions catalyze the oxidative coupling of the alkyne substrates to give diynes as undesired byproducts (Glaser coupling [9][10][11], Eglinton coupling

• incorporation of iodide in CuAAC reactions of terminal alkynes mediated by CuI (1.0 equivalent) by adequate choice of the base present in the reaction mixture [141]. With a ratio of alkyne/azide/DMAP/CuI = 1.0/3.0/0.3/1.0, they obtained 96% of the 5-iodotriazole and 4% of the Glaser coupling product. Dzyuba has

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

Pseudo five-component synthesis of 2,5-di(hetero)arylthiophenes via a one-pot Sonogashira–Glaser cyclization sequence

• Dominik Urselmann,
• Dragutin Antovic and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2011, 7, 1499–1503, doi:10.3762/bjoc.7.174

• Dominik Urselmann Dragutin Antovic Thomas J. J. Muller Institut für Organische Chemie und Makromolekulare Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany 10.3762/bjoc.7.174 Abstract Based upon a consecutive one-pot Sonogashira–Glaser coupling

• taking advantage of the high yield Sonogashira–Glaser coupling synthesis [15] of 1,4-diphenylbutadiyne starting from iodobenzene (1a) (Table 1). In addition, the final cyclization step to give 2,5-diphenylthiophene (2a) was performed under microwave heating at 120 °C for a hold time of 2 h. The solvent

• elemental analysis, compound 2j was obtained as a bishydrochloride. eN-Boc 3-iodo indole (1p) was applied as a starting material. Concept of a Sonogashira–Glaser coupling sequence. Concept of a Sonogashira–Glaser cyclization synthesis of 2,5-di(hetero)arylthiophenes. Pseudo five-component Sonogashira–Glaser

Miniemulsion polymerization as a versatile tool for the synthesis of functionalized polymers

• Daniel Crespy and
• Katharina Landfester

Beilstein J. Org. Chem. 2010, 6, 1132–1148, doi:10.3762/bjoc.6.130

• polymer dissolved in toluene. The synthesis of fluorescent conjugated particles of poly(arylene diethynylenes) in direct miniemulsions by Glaser coupling has also been reported [133]. 4,4'-Dinonyl-2,2'-bipyridine was found to be a suitable ligand for solubilizing the copper(I) chloride catalyst in the

Polar tagging in the synthesis of monodisperse oligo(p-phenyleneethynylene)s and an update on the synthesis of oligoPPEs

• Dhananjaya Sahoo,
• Susanne Thiele,
• Miriam Schulte,
• Navid Ramezanian and
• Adelheid Godt

Beilstein J. Org. Chem. 2010, 6, No. 57, doi:10.3762/bjoc.6.57

• simple – but is especially satisfying because of a trouble-free separation of the desired alkynyl–aryl coupling product and the accompanying oxidative alkyne dimerization product (Glaser coupling product). In our experience, under the standard coupling conditions – i.e. Pd(PPh3)2Cl2, CuI, piperidine, THF

• , room temperature – Glaser coupling is much faster than the alkynyl–aryl coupling. Therefore, even traces of oxygen in the reaction vessel will lead to alkyne dimerization. Furthermore, most experimentalists prefer to work up the reaction mixtures under standard conditions which means exposing the

• reaction mixture to air. Opening the flask will immediately cause any unreacted terminal alkyne to undergo Glaser coupling. This is of no concern provided the alkyne dimer and the alkynyl–aryl coupling product can be easily separated, and this is what the HOM and related HOP group guarantee since they act