Synthesis, structure and π-expansion of tris(4,5-dehydro-2,3:6,7-dibenzotropone)

• Yongming Xiong,
• Xue Lin Ma,
• Shilong Su and
• Qian Miao

Beilstein J. Org. Chem. 2025, 21, 1–7, doi:10.3762/bjoc.21.1

• The title compound (1 in Figure 1), tris(4,5-dehydro-2,3:6,7-dibenzotropone), receives this name because it can formally result from cyclotrimerization of 4,5-dehydro-2,3:6,7-dibenzotropone (2 in Figure 1). Similarly, compound 1 was called “a formal trimer of dibenzotropone” or “benzannulated tris

• graphite [22]. It was earlier prepared in Ar matrices [23] or via demetallation of a platinum complex of 4,5-dehydro-2,3:6,7-dibenzotropone [1]. More recently, compound 1 was prepared via Pd-catalyzed cyclotrimerization of 4-bromo-2,3:6,7-dibenzotropone (4 in Scheme 1) [22]. Herein we report an alternative

• yield of 90%. Then, the Ni-mediated Yamamoto coupling reaction of 6 enabled cyclotrimerization to give trione 1 in a yield of 30%. It is worth mentioning that using 1,10-phenanthroline as the ligand in the Yamamoto coupling [25][26] led to a higher yield of compound 1 than using 2,2’-bipyridine. With

Biphenylene-containing polycyclic conjugated compounds

• Cagatay Dengiz

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

• steps (Scheme 15). The initial step involved the synthesis of compound 71 in 64% yield using a cobalt-catalyzed cyclotrimerization reaction between 1,2-diethynylbenzene (5) and bis(trimethylsilyl)acetylene (70), a method commonly employed in [N]phenylene synthesis. Subsequently, treatment of compound 71

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

• )benzene through Co-catalyzed cyclotrimerization in a 45% yield. Then monoiodide NG 49 was obtained through oxidative cyclodehydronation in a high yield. From the heptagon-containing NG 49, Sonogashira coupling with p-tert-butylphenylacetylene (50) afforded 51 in a quantitative yield. Subsequent Diels

• synthesis started with the preparation of the distorted HBC analogue 49, bearing an aryl iodide for the subsequent Sonogashira cross-coupling reaction with alkyne 50 to give 51. The precursor 116 containing three pre-existing HBCs was synthesized through Co-catalyzed cyclotrimerization of compound 51

1,4,6,10-Tetraazaadamantanes (TAADs) with N-amino groups: synthesis and formation of boron chelates and host–guest complexes

• Artem N. Semakin,
• Ivan S. Golovanov,
• Yulia V. Nelyubina and
• Alexey Yu. Sukhorukov

Beilstein J. Org. Chem. 2022, 18, 1424–1434, doi:10.3762/bjoc.18.148

• has been developed via intramolecular cyclotrimerization of C=N units in the corresponding tris(hydrazonoalkyl)amines. In a similar fashion, unsymmetrically substituted TAADs having both amino and hydroxy groups at the bridge N-atoms were prepared via a hitherto unknown co-trimerization of oxime and

• hydrazone groups. The use of N-TAAD derivatives as potential ligands and receptors was showcased through forming boron chelates and host–guest complexes with water and simple alcohols. Keywords: azaadamantanes; cyclotrimerization; hydrazones; inclusion complexes; molecular recognition; Introduction

• derivatives involves the intramolecular cyclotrimerization of C=N bonds in a suitable trisimine precursor (Scheme 1). Previously, 3O-TAADs 2 were prepared by cyclization of corresponding trisoximes 1 [21]. However, this reaction is slow and reversible (upon heating adamantane structure 2 reverts to the tris

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

• corresponding cyclotrimerization products 18 or 19 (Scheme 4). The subsequent DDQ oxidation step yielded anthracenes 20 or azaanthracenes 21 in good yields (see the representative examples 20a–d and 21a–d) [38]. Recently, in a related approach, Bunz, Freudenberg, and co-workers described a useful route to

• obtain 2,3- and 2,3,6,7-halogenated anthracenes 26 by using CpCo(CO)2 as catalyst (Scheme 5) [39]. This synthesis started with a cobalt-catalyzed cyclotrimerization of previously prepared bis(propargyl)benzenes 22 and bis(trimethylsilyl)acetylene (23), affording the TMS-substituted cyclotrimerization

Design, synthesis and photophysical properties of novel star-shaped truxene-based heterocycles utilizing ring-closing metathesis, Clauson–Kaas, Van Leusen and Ullmann-type reactions as key tools

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2021, 17, 1374–1384, doi:10.3762/bjoc.17.96

• with which they can be constructed and modified. Therefore, bearing in mind a wide range of applications of truxene and its congeners, herein we reveal three novel distinctly different routes for the generation of C3-symmetric pyrrole-based truxene architectures by means of cyclotrimerization, ring

• synthetic strategies and also novel truxene-based functional materials with unique properties. Bearing in mind the importance of the truxene framework, herein, we report diverse C3-symmetric heterocyclic systems possessing the truxene scaffold in their structures by means of cyclotrimerization, ring-closing

• -allylation sequences, which in turn was assembled from the commercially available 1-indanone (1) utilizing cyclotrimerization and subsequent alkylation reactions. On the other hand, the same compound 6 was generated form triaminotruxene 4 using three-fold Clauson–Kaas reaction which in turn was assembled

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

• Joseane A. Mendes,
• Paulo R. R. Costa,
• Miguel Yus,
• Francisco Foubelo and
• Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

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

• accessible compound, namely norbornadiene (10) by involving oxidative aromatization in the presence of DDQ via an intermediate 17, as displayed in Scheme 2. As can be seen from an inspection of Scheme 2, they first performed a single step cyclotrimerization of 10 using n-BuLi and t-BuOK in 1,2-dibromoethane

• performed the similar transformation in almost identical yield using Swern oxidation reaction conditions. The diketone 19 was then transformed into the enantiopure iodonorbornanone 22 in three steps which on further regioselective Pd-catalyzed cyclotrimerization furnished the syn-benzocyclotrimer 23 in 55

• context, their journey started from syn-tris(oxonorborneno)benzene 23, obtained via palladium-catalyzed cyclotrimerization of iodonorbornene. The C3-symmetric compound 23 was then converted into the methylene groups containing compound 103 using Wittig reaction which on further treatment with

Regiodivergent synthesis of functionalized pyrimidines and imidazoles through phenacyl azides in deep eutectic solvents

• Paola Vitale,
• Luciana Cicco,
• Ilaria Cellamare,
• Filippo M. Perna,
• Antonio Salomone and
• Vito Capriati

Beilstein J. Org. Chem. 2020, 16, 1915–1923, doi:10.3762/bjoc.16.158

• pyrimidines. The cyclotrimerization of phenacyl azides containing an alkyl group (4-Me, 2b), halides (4-Cl, 4-Br and 4-F, 2c, d, and 2i) or strong electron-withdrawing groups (2-CF3, 4-CF3, 2l, m) occurs smoothly at rt generally within 4 h in a ChCl/urea eutectic mixture, thereby providing the desired

• very good yields (67–98%) when phenacyl azides are soluble in the eutectic mixture and is applicable to a range of substrates. Phenacyl azides, in turn, can also be competitively converted into 2,4-diaroyl-6-arylpyrimidines (45–88% yield) via an unprecedented cyclotrimerization reaction the key

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

• spirothiazolidinediones via a [2 + 2 + 2] cyclotrimerization reaction and the derivatives were further functionalized through DA chemistry and click reaction. Using flow cytometry, it was shown for the first time that the new benzyl alcohol derivatives of thiazolidine-2,4-dione generated here are efficient apoptosis

• ][28]. In view of the importance of thiazolidine-2,4-dione derivatives, we conceived a new synthetic strategy to diverse spirocyclic thiazolidinediones based on a [2 + 2 + 2] cyclotrimerization [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] as a key step

• 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

Synthesis of C₃-symmetric star-shaped molecules containing α-amino acids and dipeptides via Negishi coupling as a key step

• Sambasivarao Kotha and
• Saidulu Todeti

Beilstein J. Org. Chem. 2019, 15, 371–377, doi:10.3762/bjoc.15.33

• peptide dendrimers. Keywords: amino acids; cyclotrimerization; Negishi coupling; peptide; Introduction Optically active C3-symmetric molecules are valuable synthons to design dendrimers, chiral ligands, polymers, and supramolecules [1][2][3][4]. In this regard, 1,3,5-triarylbenzene derivatives are

• containing unusual AAA units through cyclotrimerization and Negishi cross-coupling reaction as key steps under operationally simple reaction conditions. Here, we have used the readily available starting materials 4-iodoacetophenone (8) and L-serine (3). The C3-symmetric building blocks prepared were coupled

Design and synthesis of C₃-symmetric molecules bearing propellane moieties via cyclotrimerization and a ring-closing metathesis sequence

• Sambasivarao Kotha,
• Saidulu Todeti and
• Vikas R. Aswar

Beilstein J. Org. Chem. 2018, 14, 2537–2544, doi:10.3762/bjoc.14.230

• groups and a benzene ring as a central core. The synthesis of these C3-symmetric molecules involves simple starting materials. Our approach to C3-symmetric compounds relies on a Diels–Alder reaction, cyclotrimerization and ring-closing metathesis as key steps. Keywords: cyclotrimerization; Diels–Alder

• transistors (OFETs) [35][36], and other optoelectronic devices. Our approach to C3-symmetric molecules containing propellane moieties involve DA reaction [37], cyclotrimerization [19] and RCM [38][39][40][41] as key steps. Results and Discussion The synthesis of propellane-bearing C3-symmetric derivatives

Unpredictable cycloisomerization of 1,11-dien-6-ynes by a common cobalt catalyst

• Abdusalom A. Suleymanov,
• Dmitry V. Vasilyev,
• Valentin V. Novikov,
• Yulia V. Nelyubina and
• Dmitry S. Perekalin

Beilstein J. Org. Chem. 2017, 13, 639–643, doi:10.3762/bjoc.13.62

• [2 + 2 + 2]-cyclotrimerization to give cyclohexene derivatives 2a,b in 70–90% yields. The rate of the reaction notably varied from experiment to experiment, but full conversion of 1a,b into 2a,b was usually achieved after 24 h. Attempts to employ 10 mol % loading of the pre-catalysts often led to

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

• 276 [106]. The new catalytic reaction which replaced a previously described four-step synthesis [107], involved a tandem aldol condensation/dehydration and cyclization of the intermediate 275 to 276 (Scheme 77). In 1999, Ikeda and Mori have presented a cyclotrimerization of enones (e.g

• . In 2000, Ikeda and Kondo have continued their studies on regioselectivity of the cyclotrimerization [109] and investigated the effects of various ligands (L) on regioselectivity and yields of this reaction (Scheme 78). In case of application of triarylphosphines (Ph3P and (o-MeC6H4)3P) as ligands

• of Ni-complex-catalyzed [2 + 2 + 2] cyclotrimerization proceeding via the intermediate 283 [110] (Scheme 79). The dimer 284 of the starting dialkyne has also been obtained. 2.3 From o-bis(dibromomethyl)benzene Erenler et al. have utilized o-bis(dibromomethyl)benzene (286) and cyclopentenone 239 to

Construction of bis-, tris- and tetrahydrazones by addition of azoalkenes to amines and ammonia

• Artem N. Semakin,
• Aleksandr O. Kokuev,
• Yulia V. Nelyubina,
• Alexey Yu. Sukhorukov,
• Petr A. Zhmurov,
• Sema L. Ioffe and
• Vladimir A. Tartakovsky

Beilstein J. Org. Chem. 2016, 12, 2471–2477, doi:10.3762/bjoc.12.241

• alkylations of amines and ammonia with azoalkenes (generated from α-halohydrazones) were demonstrated as an efficient approach to poly(hydrazonomethyl)amines – a novel class of polynitrogen ligands. An intramolecular cyclotrimerization of C=N bonds in tris(hydrazonomethyl)amine to the respective 1,4,6,10

• 1 to ammonia (Table 2) have a special significance because the expected trishydrazones 11 are obvious analogs of tris(iminomethyl)amines widely used in the catalysis of azide–alkyne cycloadditions [29][30][31][32][34]. Furthermore, intramolecular cyclotrimerization of C=N bonds in trishydrozones

• , a bis-adduct 12f was obtained in addition to trishydrazone 11f (Table 2, entry 4). Cyclization of trishydrazones 11 Upon treatment with acetic acid, trishydrazone 11b underwent a remarkable transformation to the tetraazaadamantane derivative 13b via intramolecular cyclotrimerization of C=N bonds

Elongated and substituted triazine-based tricarboxylic acid linkers for MOFs

• Arne Klinkebiel,
• Ole Beyer,
• Barbara Malawko and
• Ulrich Lüning

Beilstein J. Org. Chem. 2016, 12, 2267–2273, doi:10.3762/bjoc.12.219

• on a multigram scale. Cyclotrimerization of one equivalent of an acid chloride 5b or 5c with two equivalents of 4-bromobenzonitrile (6) was achieved using the Lewis acid antimony(V) chloride as depicted in Figure 4. The resulting colourful oxadiazinium salts 7 were mixed with aqueous ammonia solution

Recent applications of ring-rearrangement metathesis in organic synthesis

• Sambasivarao Kotha,
• Milind Meshram,
• Priti Khedkar,
• Shaibal Banerjee and
• Deepak Deodhar

Beilstein J. Org. Chem. 2015, 11, 1833–1864, doi:10.3762/bjoc.11.199

• centres (Scheme 41). Sakurai and co-workers have successfully established an enantioselective synthesis of the C3-symmetric chiral trimethylsumanene through a Pd-catalyzed cyclotrimerization and the RRM protocol as key steps [45]. Here compound 207 reacted with catalyst 1 in the presence of ethylene (24

Star-shaped tetrathiafulvalene oligomers towards the construction of conducting supramolecular assembly

• Masahiko Iyoda and
• Masashi Hasegawa

Beilstein J. Org. Chem. 2015, 11, 1596–1613, doi:10.3762/bjoc.11.175

• )[12]annulenes 28 and 29 were pepared by Sonogashira coupling of 26 with 24 and 27 with 25 in 25 and 36% yields, respectively. For the synthesis of 30 and 31, cyclotrimerization of 24 and 25 with a stoichiometric amount of PdCl2(PPh3)2 and CuI in triethylamine–THF was employed to afford 30 and 31 in 32

Cross-metathesis reaction of α- and β-vinyl C-glycosides with alkenes

• Ivan Šnajdr,
• Kamil Parkan,
• Filip Hessler and
• Martin Kotora

Beilstein J. Org. Chem. 2015, 11, 1392–1397, doi:10.3762/bjoc.11.150

• ][4][5][6][7][8][9][10][11][12][13]. Thus the ethyne moiety was used in [2 + 2 + 2] cyclotrimerization to yield aryl C-deoxyribosides [3] and in a Sonogashira reaction for the synthesis of butenolidyl C-deoxyribosides [4]. Substituted alkynyl C-deoxyribosides [5][10][11] were used in other types of

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

• -trimerization of two different alkynes with a high chemo- and regioselectivity. The Rh(I)/H8-BINAP complex catalyzed the partially intermolecular cyclotrimerization of 1,9-decadiyne (271) and diethyl acetylenedicarboxylate (272) to give [6]metacyclophane derivative 273 (Scheme 44) [177]. This approach is also

• applicable to synthesize various polyether-based cyclophanes. In this report, they have synthesized various polyether containing cyclophanes by a cross-cyclotrimerization catalyzed by a cationic rhodium(I)/H8-BINAP complex as a key step. The ether linked α,ω-diynes and dimethyl acetylenedicarboxylate were

• (Scheme 48). Ohsima and co-workers [182] have reported a rhodium-catalyzed [2 + 2 + 2] cyclotrimerization of triynes 283 in a water-organic biphasic system. The biphasic system provides dilute reaction conditions suitable for macrocyclization. Selective cross-annulation between hydrophobic diynes and

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

• yield (67%; for the spectroscopic data see Supporting Information File 1). In this intermediate the three triple bonds to be converted into a benzene ring possess only one degree of freedom: the rotation of the non-phane benzene ring around its connecting acetylene group. The cyclotrimerization of three

Site-selective covalent functionalization at interior carbon atoms and on the rim of circumtrindene, a C₃₆H₁₂ open geodesic polyarene

• Hee Yeon Cho,
• Ronald B. M. Ansems and
• Lawrence T. Scott

Beilstein J. Org. Chem. 2014, 10, 956–968, doi:10.3762/bjoc.10.94

• ]. Cyclotrimerization of 17 to the C3-symmetric trichlorodecacyclene 12 was accomplished by a triple aldol condensation of the chloro ketone 17 [48][49]. Improvements in the procedures reported previously are described in the experimental section in the Supporting Information File 1. In agreement with DFT calculations

Triphenylene discotic liquid crystal trimers synthesized by Co₂(CO)₈-catalyzed terminal alkyne [2 + 2 + 2] cycloaddition

• Bin Han,
• Ping Hu,
• Bi-Qin Wang,
• Carl Redshaw and
• Ke-Qing Zhao

Beilstein J. Org. Chem. 2013, 9, 2852–2861, doi:10.3762/bjoc.9.321

• applied to the synthesis of hexabenzocoronene DLCs through diarylethyne cyclotrimerization [51]. In this paper, we report four star-shaped DLC trimers with triphenylene discotic units by using a Co2(CO)8-catalyzed terminal alkynes [2 + 2 + 2] cycloaddition, and the trimers exhibit ordered rectangular

Ene–yne cross-metathesis with ruthenium carbene catalysts

• Cédric Fischmeister and
• Christian Bruneau

Beilstein J. Org. Chem. 2011, 7, 156–166, doi:10.3762/bjoc.7.22

• metathesis [4][5][6][7][8][9][10]. It is noteworthy that polymerization of terminal alkynes [11][12][13] and cyclotrimerization of triynes [14][15][16][17][18][19][20] with ruthenium carbene precursors is still a topic of current interest. Then, Fischer tungsten carbene complexes were used by Katz [21], and