CuAAC-inspired synthesis of 1,2,3-triazole-bridged porphyrin conjugates: an overview

• Dileep Kumar Singh

Beilstein J. Org. Chem. 2023, 19, 349–379, doi:10.3762/bjoc.19.29

• microwave conditions as described in Scheme 12. After the successful synthesis of porphyrins 63 and 66b, their corresponding rhenium complexes 64a and 67a were prepared in good yields by using [Re(CO)3Br3][NEt4]2 at 65 °C in 2 hours. In addition to these, the radiolabeled products 64b and 67b were also

• constructed from the corresponding rhenium complexes by using [99mTc(CO)3(H2O)3]+ at pH 7.4 and 90 °C temperature. Santos et al. [39] reported in 2008 the synthesis of CuAAC-ensembled 1,2,3-triazole-linked porphyrin-quinolone conjugates 70a–e by considering the biological significance of both the porphyrin

Total synthesis of grayanane natural products

• Nicolas Fay,
• Rémi Blieck,
• Cyrille Kouklovsky and
• Aurélien de la Torre

Beilstein J. Org. Chem. 2022, 18, 1707–1719, doi:10.3762/bjoc.18.181

• of enol-ether formation/Grignard addition lead to intermediate 43, from which simple acidic treatment led to rhodomollein XXII, while α-oxidation in the presence of rhenium oxide followed by acidic work-up afforded rhodomollein XX. Interestingly, Ding’s synthesis constitutes an efficient approach (22

Scope of tetrazolo[1,5-a]quinoxalines in CuAAC reactions for the synthesis of triazoloquinoxalines, imidazoloquinoxalines, and rhenium complexes thereof

• Laura Holzhauer,
• Chloé Liagre,
• Olaf Fuhr,
• Nicole Jung and
• Stefan Bräse

Beilstein J. Org. Chem. 2022, 18, 1088–1099, doi:10.3762/bjoc.18.111

• , Germany 10.3762/bjoc.18.111 Abstract The conversion of tetrazolo[1,5-a]quinoxalines to 1,2,3-triazoloquinoxalines and triazoloimidazoquinoxalines under typical conditions of a CuAAC reaction has been investigated. Derivatives of the novel compound class of triazoloimidazoquinoxalines (TIQ) and rhenium(I

• ) triazoloquinoxaline complexes as well as a new TIQ rhenium complex were synthesized. As a result, a small 1,2,3-triazoloquinoxaline library was obtained and the method could be expanded towards 4-substituted tetrazoloquinoxalines. The compatibility of various aliphatic and aromatic alkynes towards the reaction was

• complexes is a well-established method to obtain interesting materials for catalysis [31][32][33] and optoelectronics [34][35], as well as for biological applications [36][37]. Therefore, the obtained triazole and TIQ products were employed to act as ligands in rhenium tricarbonyl complexes. These are

Menadione: a platform and a target to valuable compounds synthesis

• Acácio S. de Souza,
• Ruan Carlos B. Ribeiro,
• Dora C. S. Costa,
• Fernanda P. Pauli,
• David R. Pinho,
• Matheus G. de Moraes,
• Fernando de C. da Silva,
• Luana da S. M. Forezi and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

• yield was only 10%, but after the addition of MTO and acetic anhydride, the yield increased to 46% (Table 1, entry 5) [51]. The authors suggested two simultaneous reaction pathways: a direct oxidation by rhenium bisperoxo complex and an MTO-catalyzed in situ generation of peroxyacetic acid as oxidant

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

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

• illustrated for alkyne metathesis reactions of organometallic compounds. After some stoichiometric reactions of ruthenium and rhenium half sandwich complexes [70], several reactions have been described exploiting the reactivity of acetylenic ferrocene compounds [71][72][73][74][75]. For most of these

Photochromic diarylethene ligands featuring 2-(imidazol-2-yl)pyridine coordination site and their iron(II) complexes

• Andrey G. Lvov,
• Max Mörtel,
• Anton V. Yadykov,
• Frank W. Heinemann,
• Valerii Z. Shirinian and
• Marat M. Khusniyarov

Beilstein J. Org. Chem. 2019, 15, 2428–2437, doi:10.3762/bjoc.15.235

• approach for achieving a strong impact of the photochromic reaction on the electronic structure of a coordinated metal ion. Previously reported examples of the second group ligands are collected in Figure 1. Yam et al. developed diarylethenes I [17] and II [18] and synthesized their rhenium(I) complexes

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

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

• example, azidobenziodazole was used as an efficient azidation reagent with a reactivity similar to azidobenziodoxoles [33]. Recently, the Wang group reported a rhenium catalyst-mediated oxidative dehydrogenative olefination of a C(sp3)–H bond using acetoxybenziodazole reagents [36]. To the best of our

Chemical systems, chemical contiguity and the emergence of life

• Terrence P. Kee and
• Pierre-Alain Monnard

Beilstein J. Org. Chem. 2017, 13, 1551–1563, doi:10.3762/bjoc.13.155

• using a mediator, rhenium bipyridine (a molecule similar to the ruthenium complex in Figure 2B). A concomitant development (complexity increase) of membranes and light/energy harvesting/conversion systems can thus be seen as a prerequisite in the evolution of the ancestral bioenergetics en route to the

The direct oxidative diene cyclization and related reactions in natural product synthesis

• Juliane Adrian,
• Leona J. Gross and
• Christian B. W. Stark

Beilstein J. Org. Chem. 2016, 12, 2104–2123, doi:10.3762/bjoc.12.200

• rings were introduced with excellent diastereoselectivity in a single step transformation at the final stages of the total syntheses of rollidecin C (69) and D (70) (Scheme 14). Similar rhenium-mediated type C oxidative cyclizations were also successfully applied in total syntheses of further

Iron complexes of tetramine ligands catalyse allylic hydroxyamination via a nitroso–ene mechanism

• David Porter,
• Belinda M.-L. Poon and
• Peter J. Rutledge

Beilstein J. Org. Chem. 2015, 11, 2549–2556, doi:10.3762/bjoc.11.275

• ], manganese- [19][20][21], iron- [23][24], copper- [22][31], rhenium- [26], and rhodium- [27] based reagents. The recent resurgence of interest in the nitroso–ene reaction builds on earlier work by Sharpless, Nicolas, Jørgensen and others. Sharpless reported allylic amination of 2-methyl-2-hexene with N-(p

Tetrathiafulvalene-based azine ligands for anion and metal cation coordination

• Awatef Ayadi,
• Aziz El Alamy,
• Olivier Alévêque,
• Magali Allain,
• Nabil Zouari,
• Mohammed Bouachrine and
• Abdelkrim El-Ghayoury

Beilstein J. Org. Chem. 2015, 11, 1379–1391, doi:10.3762/bjoc.11.149

• N3–H3···O1 hydrogen bonding. Titration experiments with inorganic anions showed that both ligands are suitable candidates for the sensing of fluoride anions. Ligand L2 was reacted with a Re(I) cation to yield the corresponding rhenium tricarbonyl complex 3. In the crystal structure of the newly

• prepared electroactive rhenium complex the TTF is neutral and the rhenium cation is hexacoordinated. The electrochemical behavior of the three compounds indicates that they are promising for the construction of crystalline radical cation salts. Keywords: azine ligand; fluoride sensing; rhenium

• anions are discussed. Metal cation complexation studies of the new ligands afforded the formation and the structural characterization of a neutral rhenium complex. Results and Discussion Synthesis of the ligands L1 and L2 The protocol followed for the synthesis of the new azine ligands L1 and L2 is

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

• chiral rhenium-containing phosphine F4 in the asymmetric [3 + 2] annulation of allenoates with N-tosylimines (Scheme 28) [62]. Gratifyingly, this acyclic chiral phosphine could efficiently catalyze this transformation, providing pyrroline derivatives in excellent yields (90–93%), albeit after long

Towards allosteric receptors – synthesis of β-cyclodextrin-functionalised 2,2’-bipyridines and their metal complexes

• Christopher Kremer,
• Gregor Schnakenburg and
• Arne Lützen

Beilstein J. Org. Chem. 2014, 10, 814–824, doi:10.3762/bjoc.10.77

• bipyridine structure to potentially affect the binding of another substrate. Rhenium(I), on the other hand, obviously prefers coordination to nitrogen compared to sulfur as we could demonstrate by coordinating 4,4’-dithioisocyanato-2,2’-bipyridine (14) to it. Figure 1 shows the molecular structure of this

• [(CO)3Re(14)Cl] complex obtained by X-ray diffraction analysis. Unfortunately, we were neither able to coordinate rhenium(I) to our bipyridines 1–3 nor did we succeed to prepare the rhenium complex [(CO)3Re(1)Cl] by using [(CO)3Re(14)Cl] and reacting it with aminocyclodextrin 21. Next, we tried copper

• ligand 1 forming either 1:2 or 1:1 effector:ligand complexes. Conclusion We have synthesised three new β-cyclodextrin-functionalised 2,2’-bipyridines and their complexation behaviour towards several metal salts or their complexes was investigated. Among those (pentacarbonyl)rhenium chloride and silver(I

Recent advances in transition metal-catalyzed Csp²-monofluoro-, difluoro-, perfluoromethylation and trifluoromethylthiolation

• Grégory Landelle,
• Armen Panossian,
• Sergiy Pazenok,
• Jean-Pierre Vors and
• Frédéric R. Leroux

Beilstein J. Org. Chem. 2013, 9, 2476–2536, doi:10.3762/bjoc.9.287

• induction period and demonstrated the involvement of radical species in the reaction. The authors proposed a mechanism accounting for the EPR profile of the reaction and for the results of kinetic isotope effect experiments (Figure 21). In this mechanism, rhenium intervenes in the initiation step. It acts

• as a Lewis acid and activates the hypervalent iodine reagent, which is thus able to accept an electron by the substrate; this leads to the formation of a caged pair (aryl cation radical/reduced Togni’s reagent–rhenium complex), where iodine then transfers a CF3− anion to the aryl cation. This recent

Amyloid-β probes: Review of structure–activity and brain-kinetics relationships

• Todd J. Eckroat,
• Abdelrahman S. Mayhoub and
• Sylvie Garneau-Tsodikova

Beilstein J. Org. Chem. 2013, 9, 1012–1044, doi:10.3762/bjoc.9.116

• -Br (136) and labeling through reaction with the rhenium (used for in vitro studies) and technetium precursors gave compounds 125a and 125b, respectively. Compound 125b showed decent affinity for Aβ1-42 aggregates (Ki = 32.8 nM) in vitro, although, by comparison to other benzofuran probes of similar

Fifty years of oxacalix[3]arenes: A review

• Kevin Cottet,
• Paula M. Marcos and
• Peter J. Cragg

Beilstein J. Org. Chem. 2012, 8, 201–226, doi:10.3762/bjoc.8.22

Gold-catalyzed propargylic substitutions: Scope and synthetic developments

• Olivier Debleds,
• Eric Gayon,
• Emmanuel Vrancken and
• Jean-Marc Campagne

Beilstein J. Org. Chem. 2011, 7, 866–877, doi:10.3762/bjoc.7.99

• ruthenium catalysts for asymmetric propargylic substitutions were next developed using acetone, hydrides and electron rich aromatics as nucleophiles [16][17][18]. In 2003, oxo-rhenium catalysts were introduced by Toste [19][20][21]. Substitution products were obtained in high yields with alcohols

Recent advances in the development of alkyne metathesis catalysts

• Xian Wu and
• Matthias Tamm

Beilstein J. Org. Chem. 2011, 7, 82–93, doi:10.3762/bjoc.7.12

• isolobal rhenium(VII) imido-alkylidyne complex [Re(NAr)(Ct-Bu)(ORF)] (Ar = 2,6-diisopropylphenyl, RF = CCH3(CF3)2), which is able to metathesize aliphatic alkynes [75]. In contrast, however, anionic molybdenum imido-alkylidyne complexes such as [Mo(NAr)(Ct-Bu)(ORF)]− do not promote alkyne metathesis, since

Size selective recognition of small esters by a negative allosteric hemicarcerand

• Holger Staats and
• Arne Lützen

Beilstein J. Org. Chem. 2010, 6, No. 10, doi:10.3762/bjoc.6.10

• bulky esters were not recognized by this hemicarcerand. This size selective molecular recognition could be controlled by a negative cooperative allosteric effect: coordination of a triscarbonyl rhenium chloride fragment to the bipyridine causes a conformational rearrangement that orientates the

• found to have a weak affinity for simple esters in a size selective manner in the absence of an effector whereas it does not show any binding affinity when it is coordinated to a tris(carbonyl)rhenium chloride fragment – thus showing negative cooperative allosteric behaviour. Results and Discussion

• able to form a stable complex [(CO)3Re(2)Cl] that was found to be soluble in mesitylene-d12. Usually, 2,2′-bipyridyl complexes of rhenium are kinetically almost inert. In this case, however, we were able to show that the rhenium can indeed be removed by adding ethylene diamine tetraacetic acid (EDTA

A review of new developments in the Friedel–Crafts alkylation – From green chemistry to asymmetric catalysis

• Magnus Rueping and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2010, 6, No. 6, doi:10.3762/bjoc.6.6

• ], polymolybdophosphoric acid supported silica [99], TsOH [100], FeCl3 [101][102], BiCl3 [103], Sc(OTf)3 [104] other Ru- or [105][106][107], Re-complexes [108] and even molecular iodine [109]. Toste and co-workers developed a mild rhenium-catalyzed propargylation of electron-rich arenes. In addition to principal method

• ) Propargylation of arenes with stoichiometric amounts of the Ru-allenylidene complex 86. (B) First catalytic propargylation of (hetero)arenes using a cationic Ru-complex. Diruthenium-catalyzed formation of chromenes and 1H-naphtho[2,1-b]pyrans. Rhenium(V)-catalyzed FC propargylations as a first step in the total

Recent progress on the total synthesis of acetogenins from Annonaceae

• Nianguang Li,
• Zhihao Shi,
• Yuping Tang,
• Jianwei Chen and
• Xiang Li

Beilstein J. Org. Chem. 2008, 4, No. 48, doi:10.3762/bjoc.4.48

• oxygen functions onto an unsaturated, non-functionalized carbon skeleton 271. Diversity in this approach arose from the relative timing of highly stereoselective reactions, such as the Sharpless AD reaction and the Kennedy oxidative cyclization (OC) with rhenium(VII) oxide. The convergent strategy, which

Trapping evidence for the thermal cyclization of di-(o-acetylphenyl)acetylene to 3,3'-dimethyl- 1,1'-biisobenzofuran

• Charles P. Casey,
• Neil A. Strotman and
• Ilia A. Guzei

Beilstein J. Org. Chem. 2005, 1, No. 18, doi:10.1186/1860-5397-1-18

• the transient production of A, the first biisobenzofuran. An X-ray crystal structure of meso-3 was obtained. As part of a recent study of the thermal cyclization of η2-(o-ethynylbenzoyl)rhenium complexes to rhenium isobenzofuryl carbene complexes (Scheme 1),[1] we attempted to form a rhenium complex

• data for all new compounds and X-ray crystallographic data for meso-3 (16 pages). X-ray crystallographic data for meso-3 has been deposited in the Cambridge Structural Database (CCDC # 289103). X-ray crystal structure of meso-3. Thermal cyclization of η2-(o-ethynylbenzoyl)rhenium complexes to rhenium