Tying a knot between crown ethers and porphyrins

• Maksym Matviyishyn and
• Bartosz Szyszko

Beilstein J. Org. Chem. 2023, 19, 1630–1650, doi:10.3762/bjoc.19.120

• (II) compounds 16-Pd–19-Pd exhibited conformations with the characteristic Pacman clefts, resembling their postulated solution structures and typical square-planar geometry around the palladium(II) centres. Titanium(III), vanadium(III), and chromium(III) complexes were synthesised through salt

Radical chemistry in polymer science: an overview and recent advances

• Zixiao Wang,
• Feichen Cui,
• Yang Sui and
• Jiajun Yan

Beilstein J. Org. Chem. 2023, 19, 1580–1603, doi:10.3762/bjoc.19.116

• (OMRP) is also a commonly used polymerization method, which uses transition-metal complexes such as titanium and vanadium for coordination polymerization [69]. However, due to the high cost of these complexes and their post-processing, OMRP is not widely used. The chain termination reaction of OMRP is

Asymmetric synthesis of a stereopentade fragment toward latrunculins

• Benjamin Joyeux,
• Antoine Gamet,
• Nicolas Casaretto and
• Bastien Nay

Beilstein J. Org. Chem. 2023, 19, 428–433, doi:10.3762/bjoc.19.32

• were not identified), when the reaction was performed at room temperature during 6 hours. This vanadium catalyst superseded VO(acac)2 in terms of yields [26][27]. Additional epoxidation attempts allowed to improve the dr to 82:18 (82% yield) when the reaction was left at −30 °C for 6 days

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

• ketone methylation gave access to 56. Directed C1–C5 vanadium-mediated epoxidation followed by DBU treatment and TBS deprotection afforded 57 in one pot. The tertiary alcohol 58 was obtained as a single diastereomer after hydration of position C18. Subsequent reduction with DIBAL-H gave the desired

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

• synthesis of biologically active molecules. Based on the examples mentioned above, there is a specific preference for studies of amine derivatives. However, different functional groups that may go well along with titanium catalysis need still to be explored. Vanadium-catalyzed C–H activation Vanadium is the

• twentieth most abundant element and the sixth most abundant transition metal in Earth’s crust. Rarely encountered in its metallic form, vanadium exists in oxidation states ranging from +5 to −3, including the four adjacent states +2 to +5 in aqueous solutions, and usually presents 4, 5 or 6 coordination

• numbers. The V(II) and V(V) species are reducing and oxidizing agents, respectively, whereas V(IV) is often encountered, mainly in the form of dioxovanadium ion VO2+ center [76]. Vanadium-based compounds have been reported to mediate the oxidation of alkanes to alcohols and ketones [76]. The reactions are

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

• Thiago S. Silva and
• Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

• employing the gem-disubstituted substrate 42 to obtain 43 in excellent yield and with a slightly better reaction time (1.5 days). Under improved conditions using stoichiometric amounts of vanadium hydride, the unprotected Morita–Baylis–Hillman alcohol 44 was subjected to cyclization to furnish 45 in good

• developed by Norton employed somewhat unattractive conditions, such as the necessity of maintaining a pressured hydrogen atmosphere in the case of the generation of chromium hydride, the requirement of stoichiometric amounts of vanadium hydride, and the necessity of synthesis and storage (under inert

The biomimetic synthesis of balsaminone A and ellagic acid via oxidative dimerization

• Sharna-kay Daley and
• Nadale Downer-Riley

Beilstein J. Org. Chem. 2020, 16, 2026–2031, doi:10.3762/bjoc.16.169

• to be explored. The oxidants cerium(IV) ammonium nitrate (CAN), ferric chloride hexahydrate (FeCl3·6H2O), vanadium pentoxide (V2O5), PIFA, and PIDA, in addition to SnCl4, were considered. Also investigated were 2-iodoxybenzoic acid (IBX) because of its implication in single-electron oxidation [24

Syntheses of spliceostatins and thailanstatins: a review

• William A. Donaldson

Beilstein J. Org. Chem. 2020, 16, 1991–2006, doi:10.3762/bjoc.16.166

• cleavage of the secondary triisopropylsilyl ether were prerequisites for a vanadium-catalyzed stereoselective epoxidation of the exocyclic double bond to give 90. The C-4 hydroxy group was eventually protected as a triethylsilyl ether. Through abortive attempts, Jacobsen found that the generation of the

Mechanochemical green synthesis of hyper-crosslinked cyclodextrin polymers

• Alberto Rubin Pedrazzo,
• Fabrizio Caldera,
• Marco Zanetti,
• Silvia Lucia Appleton,
• Nilesh Kumar Dhakar and
• Francesco Trotta

Beilstein J. Org. Chem. 2020, 16, 1554–1563, doi:10.3762/bjoc.16.127

• . The cyclodextrins were dried before use in an oven at 100 °C until constant weight. Elemental analyses were performed on a Thermo Scientific FlashEA 1112, using vanadium pentoxide purchased from Sigma. As planetary ball mill, a Retsch PM200 High Speed Planetary Ball Mill was used, with 20 sintered

Bacterial terpene biosynthesis: challenges and opportunities for pathway engineering

• Eric J. N. Helfrich,
• Geng-Min Lin,
• Christopher A. Voigt and
• Jon Clardy

Beilstein J. Org. Chem. 2019, 15, 2889–2906, doi:10.3762/bjoc.15.283

• ], vanadium-dependent bromoperoxidases [61][62], or methyltransferases [63]). In addition, enzymes typically classified as tailoring enzymes, such as flavin-dependent monooxygenases [64] and cytochrome P450s (CYPs) [65], were reported to be involved in noncanonical terpene cyclization. Furthermore, both

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

• (triflate). In 2014, Chen and co-workers [88] described a selective direct C(sp3)–H fluorination catalyzed by a commercially available vanadium(III) oxide with Selectfluor in good yields (Scheme 41). It is noteworthy that the catalyst and the byproduct H-TEDA could be removed easily by filtration. A simple

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• associated with the reported methodologies. Amongst various reported TMs, the participation of copper as the catalyst has been used in the largest number of cases followed by the use of palladium, rhodium, and others. It has been further observed that lanthanum, scandium, and vanadium have been very seldomly

• used for functionalization/derivatization reactions compared to MCRs in the syntheses of IPs. The role of lanthanum/scandium/nickel/vanadium in synthetic chemistry The application of scandium complexes in organic chemistry has been very scarce due to their low availability and difficulties in

• –C bond formations, and ring opening reactions [83][84][85][86][87]. Along with these nickel and vanadium were also well known to catalyze a number of organic reactions. Recent reviews published on the catalytic applications of these metals in various forms have underlined the indispensable

Cross-coupling of dissimilar ketone enolates via enolonium species to afford non-symmetrical 1,4-diketones

• Keshaba N. Parida,
• Gulab K. Pathe,
• Shimon Maksymenko and
• Alex M. Szpilman

Beilstein J. Org. Chem. 2018, 14, 992–997, doi:10.3762/bjoc.14.84

• challenging cross-coupling of two dissimilar ketone enolates. In this context Hirao achieved the intermolecular cross-coupling by taking advantage of the different oxidation potentials of boron enolates and trimethylsilyl enol ethers to achieve selectivity with vanadium (V, 0.625 equiv) as the oxidant (Scheme

Pd(OAc)₂/Ph₃P-catalyzed dimerization of isoprene and synthesis of monoterpenic heterocycles

• Dominik Kellner,
• Maximilian Weger,
• Andrea Gini and
• Olga García Mancheño

Beilstein J. Org. Chem. 2017, 13, 1807–1815, doi:10.3762/bjoc.13.175

• , titanium-, zirconium-, iron-, cobalt-, vanadium- or aluminum-based Ziegler-type catalysts lead mostly to the linear tail-to-head 2-TH dimer 2,6-dimethyl-1,3,6-octatriene (alloocimene) [27], and the use of nickel catalysts allows the preparation of the tail-to-tail dimer 2-TT (2,7-dimethyl-1,3,7-octatriene

Transition-metal-catalyzed synthesis of phenols and aryl thiols

• Yajun Liu,
• Shasha Liu and
• Yan Xiao

Beilstein J. Org. Chem. 2017, 13, 589–611, doi:10.3762/bjoc.13.58

• (Scheme 51). 1.2.4 Vanadium mediated C–H hydroxylation of arenes: In 2012, Mizuno employed divanadium-substituted phosphotungstate, and accomplished the direct hydroxylation of structurally simple arenes to phenols in the presence of H2O2 [84]. The reaction occurred at 60 °C in CH3CN/t-BuOH (1:1) and

• afforded phenols in good to excellent yields (Scheme 52). In most cases, para-hydroxylation predominantly occurred, showing good regioselectivity. This protocol is suitable for hydroxylation of simple arenes as no particular directing group was required. In 2015, the Huang group prepared a type of vanadium

• and carbamates. [RuCl2(p-cymene)]2 catalyzed hydroxylation of benzaldehydes. [RuCl2(p-cymene)]2 catalyzed hydroxylation of ethyl benzoates, benzamides and carbamates. Different regioselective ortho-hydroxylation. Ruthenium-complex-catalyzed hydroxylation of flavones. Vanadium-catalyzed hydroxylation

The reductive decyanation reaction: an overview and recent developments

• Jean-Marc R. Mattalia

Beilstein J. Org. Chem. 2017, 13, 267–284, doi:10.3762/bjoc.13.30

• experiments indicate that one of the methylene hydrogens of the formed allylamine 12 is derived from the protic solvent and the other comes from the reducing agent. Finally, an oxidative aryl–aryl coupling promoted by vanadium oxytrifluoride (VOF3) afforded phenanthroindolizidines (13, n = 1) and

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

• Laurentia venustra and exhibited antiviral activity against vesicular stomatitis virus (VSV) and herpes simplex virus type 1 (HSV-1) [157]. Hashimoto et al. reported a total synthesis of the natural product in 1988 [158][159] employing a vanadium-catalyzed epoxidation as a key step in the stereoselective

Stereo- and regioselectivity of the hetero-Diels–Alder reaction of nitroso derivatives with conjugated dienes

• Lucie Brulíková,
• Aidan Harrison,
• Marvin J. Miller and
• Jan Hlaváč

Beilstein J. Org. Chem. 2016, 12, 1949–1980, doi:10.3762/bjoc.12.184

• ]. Recently, a vanadium-catalyzed nitroso hetero-Diels–Alder reaction between hexa-2,4-dien-1-ol (69) and Boc-protected hydroxylamine 68 was reported by Hoshino [96] (Scheme 18). This reaction, with the hydroxylamine oxidized in situ to the nitroso dienophile in the presence of vanadium in different solvents

• hetero-Diels–Alder reaction by vanadium in the presence of the oxidant CHP (cumyl hydroperoxide). Regioselectivity of solution-phase nitroso hetero-Diels–Alder reaction with acyl and aryl nitroso dienophiles. Favored regioisomeric outcome for the solution and solid-phase reactions, giving hetero-Diels

The aminoindanol core as a key scaffold in bifunctional organocatalysts

• Isaac G. Sonsona,
• Eugenia Marqués-López and
• Raquel P. Herrera

Beilstein J. Org. Chem. 2016, 12, 505–523, doi:10.3762/bjoc.12.50

• derivatization. Thus, in the last decade, it has been widely employed in the field of asymmetric catalysis. Regarding the use of aminoindanol derivatives as ligands in organometallic catalytic complexes, the results have been outstanding. Examples are found in (a) the vanadium-catalyzed asymmetric oxidation of

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

• ][24][25][26]. Several new developments in the related hetero-Diels–Alder reaction of acylnitroso species have also been reported recently [27][28][29][30]. These methodologies generally involve in situ generation of the acylnitroso species, achieved using a variety of oxidants including vanadium- [28

Synthesis of phosphoramidites of isoGNA, an isomer of glycerol nucleic acid

• Keunsoo Kim,
• Venkateshwarlu Punna,
• Phaneendrasai Karri and
• Ramanarayanan Krishnamurthy

Beilstein J. Org. Chem. 2014, 10, 2131–2138, doi:10.3762/bjoc.10.220

• by vanadium trichloride gave the desired product 9 cleanly in large-scale reactions [30]. The desilylation of intermediates 11, 20 and 26 was effected by the treatment of 1 M TBAF in THF at 0 °C to room temperature. In the case of guanine derivative 23, we observed that the use of the

Halogenated volatiles from the fungus Geniculosporium and the actinomycete Streptomyces chartreusis

• Tao Wang,
• Patrick Rabe,
• Christian A. Citron and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2013, 9, 2767–2777, doi:10.3762/bjoc.9.311

• global chloroform emissions [12]. The introduction of halogens into natural products is catalysed by various known types of enzymes [13][14], including the FADH2-dependent halogenases [15], α-ketoglutarate/Fe2+-dependent halogenases [16], SAM-dependent halogenases [17][18], and vanadium-dependent

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

• -picoline can be readily oxidised via another gas-phase protocol using a fixed-bed reactor charged with vanadium pentoxide on high surface titanium dioxide (5–50 wt % vanadium). A modification of the sequence utilises a dehydrative amminolysis (ammoxidation) to furnish the corresponding 3-cyanopyridine

• , which can then be subsequently hydrolysed to nicotinic acid. The catalyst systems most commonly used in this high temperature ammoxidation are based on vanadium, molybdenum or antimony oxides supported on silica or alumina. Since the initial Chichibabin type sequence (step 1; Scheme 3) leading to 3

Camera-enabled techniques for organic synthesis

• Steven V. Ley,
• Richard J. Ingham,
• Matthew O’Brien and
• Duncan L. Browne

Beilstein J. Org. Chem. 2013, 9, 1051–1072, doi:10.3762/bjoc.9.118

• , such as the length of tubing used and the residence time required to effect a complete reaction. For subsequent work using oxygen gas, we moved to a more elegant but still simple tube-in-tube reactor setup [79]; in this case the oxidation of a lilac solution of vanadium(II) was used to indicate the

• of a sealed bottle (a) Sudan red dye is bleached by ozone gas permeating into solution through the reactor tubing, which visible (b) as a colour change from red to colourless. Similarly, solvation of oxygen gas (c) is followed by the oxidation of vanadium(III), which also has a distinct colour change

Thermodynamic and kinetic stabilization of divanadate in the monovanadate/divanadate equilibrium using a Zn-cyclene derivative: Towards a simple ATP synthase model

• Hanno Sell,
• Anika Gehl,
• Frank D. Sönnichsen and
• Rainer Herges

Beilstein J. Org. Chem. 2012, 8, 81–89, doi:10.3762/bjoc.8.8

• 0 to 7.5 mM in a system with a total concentration of vanadium [V]t of 1.5 mM at a pH value of 9.5, the ratio of vanadium bound in divanadate species rises from 5% to 23%, while the ratio of vanadium bound in monovanadate decreases from 95% to 77%. Hence, Zn-benzylcyclene 1 favors the condensation

• components leads to the mass balance equation system (3). The concentrations of the free components are the variables; the stability constants are the parameters to be optimized. In the 51V NMR titrations for the analysis of the vanadate/Zn-benzylcyclene system the total vanadium concentration [V]t at each

• system LAKE [23] for chemical equilibrium analysis and with MS-Excel [24]. Data of all titrations (78 titration points in total) were included in the calculation. The formation constants for the vanadium oxo-anions of the VO43−/H+-subsystem [21], the pKa value of Zn-benzylcyclene 1 [14] as well as the