Photomechanochemistry: harnessing mechanical forces to enhance photochemical reactions

• Francesco Mele,
• Ana M. Constantin,
• Andrea Porcheddu,
• Raimondo Maggi,
• Giovanni Maestri,
• Nicola Della Ca’ and
• Luca Capaldo

Beilstein J. Org. Chem. 2025, 21, 458–472, doi:10.3762/bjoc.21.33

• shaking a 1:1 mixture of chalcone (4.1) and 1,1,6,6-tetraphenylhexa-2,4-diyne-1,6-diol (4.2) with a test-tube shaker under irradiation with a high-pressure Hg lamp, the [2 + 2] syn-head-to-tail dimer product 4.3 was obtained selectively in 80% yield after 10 h (Scheme 4) [66]. In detail, 4.2 works as a

SOMOphilic alkyne vs radical-polar crossover approaches: The full story of the azido-alkynylation of alkenes

• Julien Borrel and
• Jerome Waser

Beilstein J. Org. Chem. 2024, 20, 701–713, doi:10.3762/bjoc.20.64

• diasteroisomer was determined to be trans. Diyne 4l could be accessed in 44% yield from the exclusive 1,2-functionalization of the corresponding ene-yne. Crude NMR of the reaction did not show the presence of an allene product which could have been formed by a 1,4-functionalization. Enol ether could also be

Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

• chemistry; Introduction The terminology “molecular tweezers” was first introduced by Chen and Whitlock in 1978 through a seminal paper [1], wherein they presented a water-soluble molecular receptor composed of two caffeine recognition units linked by a semi-rigid diyne spacer. This ingenious design enabled

Unveiling the regioselectivity of rhodium(I)-catalyzed [2 + 2 + 2] cycloaddition reactions for open-cage C₇₀ production

• Cristina Castanyer,
• Anna Pla-Quintana,
• Anna Roglans,
• Albert Artigas and
• Miquel Solà

Beilstein J. Org. Chem. 2024, 20, 272–279, doi:10.3762/bjoc.20.28

• run starting with malonate-tethered diyne 1b. In this case, the reaction was finished after 4 hours and bis(fulleroid) 2b was obtained with a 34% yield (Scheme 2). The corresponding compound 2b was analyzed by HPLC, giving only one peak. UV–vis experiments revealed the formation of a bis(fulleroid

• ) derivative (Figure S2 in Supporting Information File 1). The lower yield of 2b compared to 2a is probably due to the [2 + 2 + 2] homocoupling cycloaddition of the corresponding starting diyne, which is more favorable when the tether is a malonate rather than an NTs-sulfonamide. Among the four different [6,6

• methyl groups in the six-membered ring formed in the cycloaddition and coming from the starting diyne 1a (highlighted in red in Scheme 2). In contrast, for the minor isomer (green dots), which has Cs symmetry, the two methyl groups (highlighted in green in Scheme 2) appear as a single peak at δ = 2.40

Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

• of bisanilino-end-capped buta-1,3-diynes with TCNE, simultaneous [2 + 2] CA–RE reactions proceed for each of the two alkyne moieties of the buta-1,3-diyne skeletons, forming octacyano[4]dendralene molecules corresponding to TCBD dimers [87][88]. A well-recognized potent electron acceptor, 2,3

Biphenylene-containing polycyclic conjugated compounds

• Cagatay Dengiz

Beilstein J. Org. Chem. 2023, 19, 1895–1911, doi:10.3762/bjoc.19.141

• the synthesis of compound 81 through the utilization of the Negishi cross-coupling reaction and then the removal of TMS groups from this intermediate was achieved using TBAF, resulting in the formation of diyne 82 in 65% yield. The progression towards the synthesis of biphenylene-containing substrate

Aromatic systems with two and three pyridine-2,6-dicarbazolyl-3,5-dicarbonitrile fragments as electron-transporting organic semiconductors exhibiting long-lived emissions

• Karolis Leitonas,
• Brigita Vigante,
• Dmytro Volyniuk,
• Audrius Bucinskas,
• Pavels Dimitrijevs,
• Sindija Lapcinska,
• Pavel Arsenyan and
• Juozas Vidas Grazulevicius

Beilstein J. Org. Chem. 2023, 19, 1867–1880, doi:10.3762/bjoc.19.139

• , CDCl3) 8.10 (dd, J = 2.0, 0.6 Hz, 4H), 7.89–7.78 (m, 4H), 7.71 (dd, J = 8.7, 0.6 Hz, 4H), 7.48 (dd, J = 8.8, 2.0 Hz, 4H), 3.28 (s, 1H), 1.46 (s, 36H). 4,4'-(Buta-1,3-diyne-1,4-diylbis(4,1-phenylene))bis(2,6-bis(3,6-di-tert-butyl-9H-carbazol-9-yl)pyridine-3,5-dicarbonitrile) (6). A solution of compound 5

Construction of hexabenzocoronene-based chiral nanographenes

• Ranran Li,
• Di Wang,
• Shengtao Li and
• Peng An

Beilstein J. Org. Chem. 2023, 19, 736–751, doi:10.3762/bjoc.19.54

• helical NG 44 containing [6]helicene structure and an azulene unit (Scheme 5). Through a two-fold Diels–Alder cycloaddition from 1,4-bis(2-ethynylphenyl)buta-1,3-diyne (41) and tetracyclone 11, alkyne 42 was obtained in an 83% yield. Then unique diiodide precursor 43 was obtained by ICl-mediated

Synthesis, structure, and properties of switchable cross-conjugated 1,4-diaryl-1,3-butadiynes based on 1,8-bis(dimethylamino)naphthalene

• Semyon V. Tsybulin,
• Ekaterina A. Filatova,
• Alexander F. Pozharskii,
• Valery A. Ozeryanskii and
• Anna V. Gulevskaya

Beilstein J. Org. Chem. 2023, 19, 674–686, doi:10.3762/bjoc.19.49

• noticeable difference in the absorption maxima of diynes 5a–c and the corresponding monomers 6a–c. Moreover, the absorption maxima of compounds 5a (R = H), 5b (R = OMe), and 5c (R = CF3) are rather close to diyne 1. Figure 8 clearly demonstrates that in these cases the profiles of the long-wavelength maximum

• methoxyphenyl and the accepting protonated DMAN fragments becomes preferable (Figure 10). This is supported by a comparison of the absorption spectra of salt 11b and protonated forms of diyne 1 [15] and monomer 6b (salts 1·2HBF4 and 6b·HBF4), which demonstrates an obvious similarity of spectral curves of 11b

BINOL as a chiral element in mechanically interlocked molecules

• Matthias Krajnc and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2022, 18, 508–523, doi:10.3762/bjoc.18.53

• treated with copper iodide to obtain the phenanthroline–Cu(I) complex (R)-8. A Glaser-type coupling with the terminal alkynes 9, followed by demetalation, proceeds smoothly in 78% yield. This furnishes the desired chiral rotaxane (R)-10, consisting of a BINOL-based macrocycle and a diyne thread. The CD

• spectrum of (R)-10 shows intense signals at 321 and 344 nm, which were assigned to the diyne thread located inside the chiral environment of the BINOL-based macrocycle (see Figure 3). An example of a metal-free template approach for the synthesis of a BINOL-based [2]rotaxane was reported by Stoddart and co

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 reactions in the presence of nickel and cobalt catalysts [38]. First, they employed diyne 15 in the reaction with a series of alkynes (16) or nitriles (17) bearing a variety of functional groups including alkyl and alkene chains, hydroxy groups, and benzene and pyridine rings, to achieve the

Ring-closing metathesis of prochiral oxaenediynes to racemic 4-alkenyl-2-alkynyl-3,6-dihydro-2H-pyrans

• Viola Kolaříková,
• Markéta Rybáčková,
• Martin Svoboda and
• Jaroslav Kvíčala

Beilstein J. Org. Chem. 2020, 16, 2757–2768, doi:10.3762/bjoc.16.226

• -2,7-diyne reacted chemo- and stereoselectively in a Diels–Alder reaction with N-phenylmaleimide affording the tricyclic products as a mixture of two separable diastereoisomers, the configuration of which was estimated by DFT computations. The reported enediyne metathesis paves the way to the

• be too unstable and prone to polymerization. On the other hand, the reactivity of oxaenediyne 3 was too sluggish. Hence, 4-(allyloxy)hepta-1,6-diyne (2a) and its derivatives became the framework of choice. The key starting compound for the synthesis of oxaenediyne 2a and its derivatives was hepta-1,6

Combining enyne metathesis with long-established organic transformations: a powerful strategy for the sustainable synthesis of bioactive molecules

• Valerian Dragutan,
• Ileana Dragutan,
• Albert Demonceau and
• Lionel Delaude

Beilstein J. Org. Chem. 2020, 16, 738–755, doi:10.3762/bjoc.16.68

• stereoisomeric diyne precursors was performed first by a ring-closing alkyne metathesis in the presence of Schrock’s molybdenum catalyst. Next, the diene units were installed by intermolecular enyne metathesis of the preformed cyclic alkyne with ethylene using Grubbs second-generation ruthenium catalyst (Scheme

• related to the trinorsesquiterpene (−)‐clavukerin A, was also communicated by Metz et al. [79] using an enyne metathesis reaction as a key step. The authors performed a relay metathesis of the trienyne or diene–diyne precursors in the presence of the second-generation Grubbs catalyst (Scheme 14). The

• enantiopure trienyne or diene–diyne metathesis precursors were readily obtained from (S)-citronellal by a highly diastereoselective organocatalytic Michael addition. Erogorgiaene An exceptionally stereoselective synthesis of erogorgiaene (12) (95% E-selectivity) was reported by Hoveyda et al. [80]. They

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

• . In this regard, the required diyne precursor of thiazolidinedione was prepared from N-methylthiazolidine-2,4-dione (5a) and propargyl bromide (6a) in the presence of K2CO3 in DMF to afford the dipropargylated intermediate thiazolidinedione 7a in 85% yield. Diyne 7a was then reacted with propargyl

• peaks in the carbonyl region of the 13C NMR spectrum and no third carbonyl peak (Figure 1). Finally, mass spectral (HRMS) data confirmed the molecular formula. Next, we prepared the diyne precursors and examined the [2 + 2 + 2] cyclotrimerization strategy with different propargyl halides 6 to obtain

• generate new derivatives suitable for the multiple interaction sites. Further, the antitumour activity of these compounds were studied. Therefore, we synthesized the required diyne derivatives of thiazolidinedione for [2 + 2 + 2] cycloaddition, in the presence of propargyl bromide and K2CO3 in DMF. The

Formation of alkyne-bridged ferrocenophanes using ring-closing alkyne metathesis on 1,1’-diacetylenic ferrocenes

• Celine Bittner,
• Dirk Bockfeld and
• Matthias Tamm

Beilstein J. Org. Chem. 2019, 15, 2534–2543, doi:10.3762/bjoc.15.246

• variety of applications [86][87][88][89][90]. An example (complex V) with an additional diyne moiety is given in Figure 2 [91]. To the best of our knowledge, no ferrocenophanes formed via RCAM have been reported to date. With this contribution, we would like to present the first RCAM of 1,1’-diacetylenic

• behaviour can be ascribed to the fact that Ag(SbF6) acts as a stronger oxidant in DCM compared to THF solution [98]. Well-defined catalysts for alkyne metathesis. Examples for a ferrrocenic thiacrown ether complexing palladium (IV), and a dicationic ferrocenophane (V) featuring a diyne bridge for ion

Unprecedented nucleophile-promoted 1,7-S or Se shift reactions under Pummerer reaction conditions of 4-alkenyl-3-sulfinylmethylpyrroles

• Takashi Go,
• Akane Morimatsu,
• Hiroaki Wasada,
• Genzoh Tanabe,
• Osamu Muraoka,
• Yoshiharu Sawada and
• Mitsuhiro Yoshimatsu

Beilstein J. Org. Chem. 2018, 14, 2722–2729, doi:10.3762/bjoc.14.250

• yields. Corresponding pyrroloselenides 6a–f were prepared by applying a similar synthetic sequence; however, the selenoxides could not be obtained by implementing the usual reaction conditions. The structure of the products derived from the amination–cyclisation reaction of sulfanyl 1,6-diyne 1a was

• -bromobenzenesulfonyl derivative, which was expected to act as a good substrate for the isolation of crystals, and performed the same sequential process of sulfanyl-1,6-diynes to the oxazine derivatives (Scheme 7). Hydroamination–cyclisation of diyne 1 with N-allyl-p-bromobenzenesulfonamide 3g and the successive

• . Proposed mechanism. Crossover experiment. Lewis acid-catalysed cyclization of diols. Sequential process of sulfanyl-1,6-diyne 1 to 4H-pyrrolo[3,4-g]oxazine 25g. Screening the reaction conditions for the Pummerer reactions. DFT Calculation of the two pathways: from 14 to 15x or from 14 to 21x. Supporting

Cobalt- and rhodium-catalyzed carboxylation using carbon dioxide as the C1 source

• Tetsuaki Fujihara and
• Yasushi Tsuji

Beilstein J. Org. Chem. 2018, 14, 2435–2460, doi:10.3762/bjoc.14.221

• pyrones 44a–g in good-to-high yields within 1 h (Scheme 40). Ester, ketone, and hydroxy groups were tolerated in the reaction. In the case of an unsymmetrical diyne bearing methyl and isopropyl groups (43g), a mixture of regioisomers 44g + 44g′ was obtained in high yield with high regioselectivity. For

• this transformation, the reaction pathways depicted in Scheme 41 can be envisaged. The Rh(I) species A reacts with a diyne to afford rhodacycle B (step a). Then, the reaction of B with CO2 produces the seven-membered rhodium intermediate C (step b), from which reductive elimination occurs to yield its

• corresponding pyrone and the Rh(I) species A (step c). Alternatively, the oxidative cyclization of A proceeds as one of the C–C triple bonds of the diyne and CO2 react regioselectively, and rhodacycle D is subsequently formed (step d). Then, the insertion of the alkyne into the Rh–C bond occurs to give

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

[3 + 2]-Cycloaddition reaction of sydnones with alkynes

• Veronika Hladíková,
• Jiří Váňa and
• Jiří Hanusek

Beilstein J. Org. Chem. 2018, 14, 1317–1348, doi:10.3762/bjoc.14.113

• preferentially oxidize one equivalent of phenylacetylene to give 1,4-diphenylbuta-1,3-diyne (isolated in 80% yield) and the evolved Cu(I) salt then forms Cu(I) acetylide with a second equivalent of phenylacetylene. Thus formed Cu(I) acetylide is then responsible for gradual increasing of 1,4-pyrazole occurrence

Progress in copper-catalyzed trifluoromethylation

• Guan-bao Li,
• Chao Zhang,
• Chun Song and
• Yu-dao Ma

Beilstein J. Org. Chem. 2018, 14, 155–181, doi:10.3762/bjoc.14.11

• Trifluoromethylated acetylenes were widely used in medicinal, agrochemical, and material science. In 2010, Qing and coworkers [60] firstly reported a copper-mediated trifluoromethylation of terminal alkynes using TMSCF3 as a trifluoromethyl source. (Scheme 39). At the beginning of the experiment, undesired diyne

• byproduct was formed as major product instead of E. The author attributed this phenomenon to the competitive formation of bis-alkynyl–Cu complex D, which would produce the undesired diyne byproduct (Scheme 39). In order to solve this problem, the substrates were added by using a syringe pump over a period

Recent applications of click chemistry for the functionalization of gold nanoparticles and their conversion to glyco-gold nanoparticles

• Vivek Poonthiyil,
• Thisbe K. Lindhorst,
• Vladimir B. Golovko and
• Antony J. Fairbanks

Beilstein J. Org. Chem. 2018, 14, 11–24, doi:10.3762/bjoc.14.2

• had been deposited on a carbon electrode with an azide-terminated sialic acid derivative [74]. Firstly, AuNPs were electro-deposited on a carbon electrode. Then a solution of an alkyne-terminated disulphide (4,7,10,13,38,41,44,47-octaoxa-25,26-dithiapentaconta-1,49-diyne) was ‘dropped over’ the AuNP

Total synthesis of elansolids B1 and B2

• Liang-Liang Wang and
• Andreas Kirschning

Beilstein J. Org. Chem. 2017, 13, 1280–1287, doi:10.3762/bjoc.13.124

• ) was the installation of the side chain at C1–C13. The synthesis relied on two consecutive Sonogashira–Hagihara cross-coupling reactions that provided the ene–diyne system (C10–C15) 10 in good yield. However, partial hydrogenation (only the zinc–copper couple worked) furnished the desired (Z,E,Z

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

• -activation process, to establish an additional bond to one of the adamantyl groups (8 in Scheme 3b) [32]. The simplest diyne 4d with R = H, in contrast, gave a ring enlargement from six to seven members together with a 1,2-oxygen shift instead (9 in Scheme 3c) [33]. This clearly demonstrates that the

• , with benzylacetylene, the expected diyne 4e (Scheme 3d) is obtained, with only traces of monosubstituted compounds. However, with a 3:1 ratio, the main product is formed by reaction of only one equivalent of lithium salt with the C=N double bond, leaving the carbonyl group intact. In addition, the

Synthesis of 1-indanones with a broad range of biological activity

• Marika Turek,
• Dorota Szczęsna,
• Marek Koprowski and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48

• , only para isomers 279 were formed in moderate 33% and 49% yields, respectively. On the contrary, when oxazolines 280 or 281 were used as ligands, mainly meta isomers 278 were formed with high yields. Cheng et al. have obtained 1-indanone 285 from octa-1,7-diyne (282) and cyclopentenone 239 as a result

• ranged from 1:2 to 2:3 with a preference to 310a–315a regioisomers. An interesting approach to the synthesis of 1-indanones and 1-indenones is based on the hexadehydro-Diels–Alder (HDDA) reaction in which an alkyne reacts in the [4 + 2] cycloaddition with diyne and forms a reactive benzyne species as a

• cycloaddition reaction. In the “normal” mode of this reaction, cyclization takes place between the triple bond in α,β-position and the diyne in γ’,ε’-position to give 320. In the “abnormal” mode, the cyclization takes places between the triple bond in γ’-position and the diyne in α,γ-position to give 321. Hoye

Stereodynamic tetrahydrobiisoindole “NU-BIPHEP(O)”s: functionalization, rotational barriers and non-covalent interactions

• Golo Storch,
• Sebastian Pallmann,
• Frank Rominger and
• Oliver Trapp

Beilstein J. Org. Chem. 2016, 12, 1453–1458, doi:10.3762/bjoc.12.141

• well as rotational barriers are studied in solution by (D)HPLC techniques. Results and Discussion Synthesis of tetrahydrobiisoindole “NU-BIPHEP(O)s” The rhodium catalyzed double [2 + 2 + 2] cycloaddition of 1,4-bis(diphenylphosphinoyl)buta-1,3-diyne and a variable diyne compound is the key step in the

• functionalization at the secondary amine position, we changed the strategy and used N-Boc dipropargylamine as the diyne compound (Figure 1A). The double cycloaddition product 1c was obtained in 77% yield. In accordance with the report of Doherty et al., very slow addition of the diyne compound via syringe pump was