(E,Z)-1,1,1,4,4,4-Hexafluorobut-2-enes: hydrofluoroolefins halogenation/dehydrohalogenation cascade to reach new fluorinated allene

• Nataliia V. Kirij,
• Andrey A. Filatov,
• Yurii L. Yagupolskii,
• Sheng Peng and
• Lee Sprague

Beilstein J. Org. Chem. 2024, 20, 452–459, doi:10.3762/bjoc.20.40

• significantly. One of the new and budding directions in recent years is the stereoselective olefin metathesis processes based on catalysis by complexes of molybdenum, tungsten and ruthenium [3][4][5]. The first publications have recently appeared that molybdenum complexes can catalyze cross-metathesis of butene

Metal-catalyzed coupling/carbonylative cyclizations for accessing dibenzodiazepinones: an expedient route to clozapine and other drugs

• Amina Moutayakine and
• Anthony J. Burke

Beilstein J. Org. Chem. 2024, 20, 193–204, doi:10.3762/bjoc.20.19

• suitable surrogate. Not only that, the use of safer to use surrogates, is important for use in enabling technologies, like continuous flow and microwave-heated reactions. In fact, CO-free aminocarbonylation reactions are well known, and molybdenum hexacarbonyl (Mo(CO)6) is a very useful surrogate having

• (entry 1, Table 1). Next, the same procedure was carried out in the presence of molybdenum hexacarbonyl (Mo(CO)6, 2 equiv) as CO surrogate, under the previous conditions, but again we only observed the formation of intermediate 3a in 21% yield (entry 2, Table 1). Changing the ligand to triphenylphosphine

• reactions described in Table 1, involving Mo(CO)6 were 20 °C higher than the reactions described in Table 2 and/or (b) Mo(CO)6 acts as a co-catalyst. An investigative study was thus undertaken to elucidate the effect of the molybdenum reagent on the reaction using a simple model system consisting of aniline

A deep-red fluorophore based on naphthothiadiazole as emitter with hybridized local and charge transfer and ambipolar transporting properties for electroluminescent devices

• Suangsiri Arunlimsawat,
• Patteera Funchien,
• Pongsakorn Chasing,
• Atthapon Saenubol,
• Taweesak Sudyoadsuk and
• Vinich Promarak

Beilstein J. Org. Chem. 2023, 19, 1664–1676, doi:10.3762/bjoc.19.122

• )/molybdenum trioxide (MoO3) (6 nm)/Al (100 nm), respectively (Figure 6a), where the MgF2 layer was employed as an insulator. During the measurements, varied maximum voltages were applied during the pulse for extracting the charges while keeping the pulse duration and offset voltage of 10 μs and 5 V for the

Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

• Cécile Alleman,
• Charlène Gadais,
• Laurent Legentil and
• François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

• Langemann reported an efficient and short total synthesis of the natural product dactylol (72) (Scheme 12) [37]. The main originality of this work was the use of the Schrock molybdenum carbene catalyst 73 for the ring-closing metathesis reaction. The metathesis precursor 70 was obtained in 4 steps from

• commercial cyclopentenone 69. Protection of the alcohol function was mandatory prior to the cyclization as the free alcohol substrate failed to cyclize. As proposed by the authors, interaction between the free alcohol 70 and the molybdenum metal center may explain the reaction inhibition. Thus, after

An isoxazole strategy for the synthesis of 4-oxo-1,4-dihydropyridine-3-carboxylates

• Timur O. Zanakhov,
• Ekaterina E. Galenko,
• Mikhail S. Novikov and
• Alexander F. Khlebnikov

Beilstein J. Org. Chem. 2022, 18, 738–745, doi:10.3762/bjoc.18.74

• -triaryl-substituted and 1,2,5,6-tetrasubstituted nicotinates. Keywords: isoxazole; methyl nicotinate; molybdenum hexacarbonyl; 4-pyridone; ring expansion; Introduction Pyridine moieties are present in many natural products, drugs, pesticides and industrial materials. Pyridine fragments are used in drugs

Direct synthesis of anomeric tetrazolyl iminosugars from sugar-derived lactams

• Michał M. Więcław and
• Bartłomiej Furman

Beilstein J. Org. Chem. 2021, 17, 115–123, doi:10.3762/bjoc.17.12

• ] and Huang [20][21]. Adolfsson expanded this by the use of molybdenum-based catalysts [22]. The reductive approach allows the issues associated with nucleophilic addition to amide carbonyl groups to be overcome and as such is finding its place in a growing number of synthetic applications [10]. 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

• for other catalytic reactions, e.g., for the Pauson–Khand reaction [14]. In the enantioselective RCM, prochiral trienes have been most often employed, leading to chiral cycloalkenes. The Schrock molybdenum precatalysts [15][16][17] proved to be more effective than the Grubbs or Collins ruthenium

Synthesis of purines and adenines containing the hexafluoroisopropyl group

• Viacheslav Petrov,
• Rebecca J. Dooley,
• Alexander A. Marchione,
• Elizabeth L. Diaz,
• Brittany S. Clem and
• William Marshall

Beilstein J. Org. Chem. 2020, 16, 2739–2748, doi:10.3762/bjoc.16.224

• were determined using the peak fitting utility in ACDLabs Spectrus Processor software (v. 2018.1.1). X-ray diffraction X-ray data for 7a, 2a, 3a, 4a, and 6a were collected at −100 °C using a Bruker APEX-II CCD system equipped with a sealed tube molybdenum source and a graphite monochromator. The

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

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

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

• from the corresponding terminal diacetylenic ferrocenes [fc{CO2(CH2)nC≡CH}2] (1a: n = 2; 1b: n = 3) through ring-closing alkyne metathesis (RCAM) utilizing the highly effective molybdenum catalyst [MesC≡Mo{OC(CF3)2CH3}3] (MoF6; Mes = 2,4,6-trimethylphenyl). The metathesis reaction occurs in short time

• isolated from THF solution. Keywords: alkyne metathesis; ferrocene; homogeneous catalysis; molybdenum; terminal alkynes; Introduction Alkyne metathesis, the reversible making and breaking of carbon–carbon triple bonds, is clearly gaining more attention. Not only could a great number of active catalysts

• alkyne metatheses. A selection of such complexes is shown in Figure 1. Molybdenum alkylidyne complex I with siloxide ligands (X = OSiPh3) [10][11] is widely used in natural product synthesis, predominantly through ring-closing alkyne metathesis (RCAM) [12][13][14][15][16][17][18][19][20]. The metathesis

A novel three-component reaction between isocyanides, alcohols or thiols and elemental sulfur: a mild, catalyst-free approach towards O-thiocarbamates and dithiocarbamates

• András György Németh,
• György Miklós Keserű and
• Péter Ábrányi-Balogh

Beilstein J. Org. Chem. 2019, 15, 1523–1533, doi:10.3762/bjoc.15.155

• isocyanides and sulfur [76] can be enhanced using various catalysts such as selenium, molybdenum, copper, rhodium [77][78][79][80][81][82] or tellurium [83] providing the isothiocyanates in excellent yields. These approaches on the other hand suffer from the use of heavy metals, toxic chalcogens and/or long

Application of olefin metathesis in the synthesis of functionalized polyhedral oligomeric silsesquioxanes (POSS) and POSS-containing polymeric materials

• Patrycja Żak and
• Cezary Pietraszuk

Beilstein J. Org. Chem. 2019, 15, 310–332, doi:10.3762/bjoc.15.28

• application of molybdenum-based complexes in modification of silsesquioxanes (Figure 3), which can be explained as related to the sensitivity of these complexes toward atmospheric oxygen, moisture and functional groups of reagents. Review Cross metathesis of vinyl-substituted silsesquioxanes The first

• metathetic transformations of vinyl-substituted silsesquioxanes and spherosilicates (Figure 4) were reported by Feher in 1997 [8]. In the presence of molybdenum alkylidene complex Mo-1 octavinylsilsesquioxane (OVS) underwent cross metathesis of terminal and internal olefins, functionalized olefins (such as

Catalysis of linear alkene metathesis by Grubbs-type ruthenium alkylidene complexes containing hemilabile α,α-diphenyl-(monosubstituted-pyridin-2-yl)methanolato ligands

• Tegene T. Tole,
• Johan H. L. Jordaan and
• Hermanus C. M. Vosloo

Beilstein J. Org. Chem. 2019, 15, 194–209, doi:10.3762/bjoc.15.19

• (Figure 1). Of course, the role of the so-called Schrock metal carbenes based on tungsten and molybdenum should not be ignored in the success story of the alkene metathesis reaction but it is not the focus of this article. The large number of ruthenium alkylidene precatalysts that has been developed is

The activity of indenylidene derivatives in olefin metathesis catalysts

• Maria Voccia,
• Steven P. Nolan,
• Luigi Cavallo and
• Albert Poater

Beilstein J. Org. Chem. 2018, 14, 2956–2963, doi:10.3762/bjoc.14.275

• molybdenum systems appear to confer the right environment that allows a productive alkene metathesis [10][11]. Little productive reactivity has been uncovered using other metals [12][13][14]. Apart from the metal, ruthenium-based olefin metathesis has seen several changes during the last decades, modifying

• molybdenum counterparts, they display sensitivity to decomposition while in solution [24][25]. Understanding and/or the elimination of potential pathways that leads to catalyst decomposition is extremely important [26][27][28], since any knowledge obtained in this area can guide the catalyst design efforts

MoO₃ on zeolites MCM-22, MCM-56 and 2D-MFI as catalysts for 1-octene metathesis

• Hynek Balcar,
• Martin Kubů,
• Naděžda Žilková and
• Mariya Shamzhy

Beilstein J. Org. Chem. 2018, 14, 2931–2939, doi:10.3762/bjoc.14.272

• concentration of the acidic centres resulting in catalysts of moderate activity but with the highest selectivity. Keywords: metathesis; molybdenum oxide; 1-octene; thermal spreading; zeolites; Introduction Molybdenum oxide on silica, alumina or silica-alumina belongs to the well-known and long-time used

• . However, the conversions to tetradecene were rather low (maximum conversion about 20% was achieved). Higher catalytic activity of molybdenum oxide on zeolitic support in metathesis may be ascribed to the higher acidity of supports. The enhancing effect of Brønsted acidity on the catalytic activity has

• been already described [6] and it assumed that most of Mo active species in zeolite-based catalysts are formed by reacting molybdenum oxide with Si-O(H)-Al groups [12][27]. Similarly, Lim et al. showed recently [28], that Brønsted acid sites improve dispersion of molybdenum oxide on the surface

Efficient catalytic alkyne metathesis with a fluoroalkoxy-supported ditungsten(III) complex

• Henrike Ehrhorn,
• Janin Schlösser,
• Dirk Bockfeld and
• Matthias Tamm

Beilstein J. Org. Chem. 2018, 14, 2425–2434, doi:10.3762/bjoc.14.220

• Henrike Ehrhorn Janin Schlosser Dirk Bockfeld Matthias Tamm Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany 10.3762/bjoc.14.220 Abstract The molybdenum and tungsten complexes M2(OR)6 (Mo2F6, M = Mo, R = C(CF3)2Me

• were initially based on a design strategy inspired by the structure of highly active olefin metathesis catalysts, the Schrock-type molybdenum and tungsten alkylidene complexes [13][14][15]. Imidazolin-2-iminato ligands were used to modify Schrock-type alkylidyne complexes, resulting in new active

• ), was employed, which gave rise to the corresponding molybdenum and tungsten benzylidyne complexes [18][19][20]. In addition to these, several well-defined alkylidyne complexes have been developed and successfully utilized in alkyne metathesis in the past decade. The molybdenum alkylidyne complex with

The enzymes of microbial nicotine metabolism

• Paul F. Fitzpatrick

Beilstein J. Org. Chem. 2018, 14, 2295–2307, doi:10.3762/bjoc.14.204

• involved in uptake of molybdenum and biosynthesis of the molybdopterin cofactor [11]. The mechanism of Scheme 2 can be written for nicotine dehydrogenase by analogy to the mechanism of xanthine oxidoreductase [8]. Here, the oxygen that is incorporated into the product initially comes from water, and the

Phosphorus pentasulfide mediated conversion of organic thiocyanates to thiols

• Chandra Kant Maurya,
• Avik Mazumder and
• Pradeep Kumar Gupta

Beilstein J. Org. Chem. 2017, 13, 1184–1188, doi:10.3762/bjoc.13.117

• , Zn–HCl, catalytic hydrogenation (H2–molybdenum disulfide) and metal hydrides like LAH [12][13][14][15][16][17]. These methods, however, suffer from disadvantages like slow reaction rates, poor product yields, involvement of expensive and harsh reagents [16] and predominant side reactions leading to

Synthesis and characterization of fluorinated azadipyrromethene complexes as acceptors for organic photovoltaics

• Forrest S. Etheridge,
• Roshan J. Fernando,
• Sandra Pejić,
• Matthias Zeller and
• Geneviève Sauvé

Beilstein J. Org. Chem. 2016, 12, 1925–1938, doi:10.3762/bjoc.12.182

• 40 mg/mL, 1:0.8 donor-to-acceptor ratio, were spun coat at 800 rpm for 40 s and 2000 rpm for 2 s and annealed at 120 °C for 15 min. Molybdenum oxide (10 nm) and silver (80 nm) were thermally evaporated in sequence under a vacuum pressure of ≈3 × 10−6 Torr using an Angstrom Engineering Evovac thermal

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

• example, Mo(VI) peroxo complexes 64 and 65 were employed as the catalysts and 90% H2O2 served as the oxidizer (Table 5). The results obtained from the reactions using molybdenum systems have stimulated the search for new catalysts based on transition metal complexes. The usage of the platimum complex

On the mechanism of imine elimination from Fischer tungsten carbene complexes

• Philipp Veit,
• Christoph Förster and
• Katja Heinze

Beilstein J. Org. Chem. 2016, 12, 1322–1333, doi:10.3762/bjoc.12.125

• related pentacarbonyl complexes of bis[di(isopropyl)amino]carbene 10 [49] M(CO)5(10) (M = Cr, Mo, W) readily decarbonylate at room temperature to give the tetracarbonyl complexes M(CO)4(κC,κN-10) with a side-on coordinated carbene ligand (Scheme 1e) [50][51][52]. Under CO atmosphere, the molybdenum and

Aluminacyclopentanes in the synthesis of 3-substituted phospholanes and α,ω-bisphospholanes

• Vladimir A. D’yakonov,
• Alevtina L. Makhamatkhanova,
• Rina A. Agliullina,
• Leisan K. Dilmukhametova,
• Tat’yana V. Tyumkina and
• Usein M. Dzhemilev

Beilstein J. Org. Chem. 2016, 12, 406–412, doi:10.3762/bjoc.12.43

• with molybdenum hexacarbonyl. The structure of the complexes was proved by multinuclear 1H, 13C, and 31P spectroscopy. Keywords: aluminacyclopentanes; Dzhemilev reaction; molybdenum complexes; phospholanes; zirconium complexes; Introduction A widely used approach for the synthesis of cyclic

• molybdenum complexes. For example, 3-hexyl-1-phenylphospholane and 3-benzyl-1-methylphospholane react with Mo(CO)6 furnishing molybdenum complexes 13b and 14g (Scheme 7). The complex formation is evidenced by changes in the NMR spectral parameters of compounds 13b and 14g in relation to the initial

• of the phosphorus atom incorporated in the molybdenum complex. In addition, the С-5 signal in the 13С NMR spectra is shifted downfield by ca. 8 ppm and the constant JPC5 = 24.1 Hz (for example, for 13b) is much higher not only compared to the corresponding atom in the initial phospholane 2b but also

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

• -chlorophenyl)hydroxylamine using a molybdenum complex [32], a process that was made catalytic by adding excess N-phenylhydroxylamine [33]. The combination of iron(II) phthalocyanines [34][35] or iron(II)/iron(III) chloride [36][37][38] and N-phenylhydroxylamine effect allylic amination reactions that are

Olefin metathesis in air

• Lorenzo Piola,
• Fady Nahra and
• Steven P. Nolan

Beilstein J. Org. Chem. 2015, 11, 2038–2056, doi:10.3762/bjoc.11.221

• solvents, and yielded products with high enantiomeric excess (ee). The results where comparable to previously reported results for molybdenum-catalyzed systems [57], although the latter was used under inert conditions. In 2003, Blechert et al. reported the first systematic example of olefin metathesis in