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

• photocatalytic decomposition of water on illuminated titanium dioxide (TiO2) electrodes in 1972 [27]. This critical report began the field of semiconductor HPC, and in combination with the development of organic electronics, established fundamental principles that still underpin much of the cutting-edge

• , brookite, and rutile (Figure 3A). The different lattice structures influence the atomic orbital environments and energy, which alters the photophysical and charge transport properties of the material, which has been studied in great detail [78][79][80][81][82]. The titanium and oxygen atomic orbitals

• shown for MnO2 deposited on titanium sheets and nanotubes for photocatalysis [152]. Ray and Lalman deposited nanofiber TiO2 to a metal support via electrospinning a solution of titanium tetraisopropoxide and polyvinyl acetate (PVAc) to form a TiO2-PVAc composite material. TiO2-PVAc was subsequently

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

Chiral terpene auxiliaries V: Synthesis of new chiral γ-hydroxyphosphine oxides derived from α-pinene

• Anna Kmieciak and
• Marek P. Krzemiński

Beilstein J. Org. Chem. 2019, 15, 2493–2499, doi:10.3762/bjoc.15.242

• phosphine with poly(methylhydrosiloxane) in the presence of titanium(IV) isopropoxide (Scheme 4). The work-up of the reaction mixture with 25% HF allowed to remove silicon and titanium impurities and purification of 23 by column chromatography on silica gel yielded the product in 62%. 4

• )isoverbanol (23) Phosphine oxide 22 (0.221 g, 0.6 mmol) was dissolved in dry toluene (2 mL) in a Schlenk flask under nitrogen. Then, poly(methylhydrosiloxane) (PMHS, 0.3 mL) and titanium(IV) isopropoxide (0.672 g, 0.7 mL, 2.4 mmol) were added dropwise to the solution. The reaction mixture was stirred for 24 h

Synthesis of polydicyclopentadiene using the Cp₂TiCl₂/Et₂AlCl catalytic system and thin-layer oxidation of the polymer in air

• Zhargolma B. Bazarova,
• Ludmila S. Soroka,
• Alex A. Lyapkov,
• Мekhman S. Yusubov and
• Francis Verpoort

Beilstein J. Org. Chem. 2019, 15, 733–745, doi:10.3762/bjoc.15.69

• Abstract The polymerization process of dicyclopentadiene using a multicomponent catalytic system based on bis(cyclopentadienyl)titanium dichloride and diethylaluminum chloride was studied. It was demonstrated that the application of an excess of the aluminum component leads to the formation of stable

• through the layers. Consequently, this leads to the transition of the oxidation from a kinetic mode into a diffusive mode. Such structural changes do not occur in a polymer that was stabilized by adding an antioxidant. Keywords: bis(cyclopentadienyl)titanium dichloride; cationic polymerization; oxidation

• hardness of the systems and contributes to the generation of products having a linear structure. To realize this, the usage of a catalyst component bearing already organic ligands in its structure – bis(cyclopentadienyl)titanium dichloride (Cp2TiCl2) is proposed. Polymers based on DCPD, obtained by

Synthesis of nonracemic hydroxyglutamic acids

• Dorota G. Piotrowska,
• Iwona E. Głowacka,
• Andrzej E. Wróblewski and
• Liwia Lubowiecka

Beilstein J. Org. Chem. 2019, 15, 236–255, doi:10.3762/bjoc.15.22

• of a chiral auxiliary with lithium dibutylcuprate. Next, titanium tetrachloride-catalyzed cyanation secured another carboxy group and after a few transformations an oxazolidinone (4S,5R)-39 was obtained as a major (7:1) product readily purified chromatographically. To complete the synthesis of (2S,3R

• final step transesterification of methyl to benzyl esters was successfully performed in the presence of titanium(IV) benzyloxide to afford dibenzyl esters 102 and 103, respectively. Their hydrogenolysis cleanly produced (2S,3S,4S)-104 and (2S,3S,4S)-105 [103]. From tartaric acids Four-carbon chirons

Synthesis of unnatural α-amino esters using ethyl nitroacetate and condensation or cycloaddition reactions

• Glwadys Gagnot,
• Vincent Hervin,
• Eloi P. Coutant,
• Sarah Desmons,
• Racha Baatallah,
• Victor Monnot and
• Yves L. Janin

Beilstein J. Org. Chem. 2018, 14, 2846–2852, doi:10.3762/bjoc.14.263

• condensation reactions between aldehydes 3 or acetals 5 and ethyl nitroacetate (4). However, the high yield condensations with aldehydes 3 which were reported for some examples [3][4] require more than stoichiometric amounts of titanium tetrachloride thus leading to considerable amounts of metal-containing

• successful. Such phenomenon probably accounts for the modest yields reported in many instances even when using titanium tetrachloride to achieve this condensation [5][6]. Concerning the reduction of the nitroacrylates 2 into the α-nitro esters 6, tangible but still modest yield improvements were observed

Learning from B₁₂ enzymes: biomimetic and bioinspired catalysts for eco-friendly organic synthesis

• Keishiro Tahara,
• Ling Pan,
• Toshikazu Ono and
• Yoshio Hisaeda

Beilstein J. Org. Chem. 2018, 14, 2553–2567, doi:10.3762/bjoc.14.232

• 1 by replacing reductases with semiconductor photosensitizers and molecular photosensitizers. For example, we reported an ultraviolet-light-driven system using titanium dioxide (TiO2) semiconductor [95][96][97][98][99][100][101]. The conductive band electron of TiO2 (Ered = −0.5 V vs NHE in neutral

Synthesis of eunicellane-type bicycles embedding a 1,3-cyclohexadiene moiety

• Alex Frichert,
• Peter G. Jones and
• Thomas Lindel

Beilstein J. Org. Chem. 2018, 14, 2461–2467, doi:10.3762/bjoc.14.222

• The first synthesis of diterpenoid eunicellane skeletons incorporating a 1,3-cyclohexadiene moiety is presented. Key step is a low-valent titanium-induced pinacol cyclization that proved to be perfectly diastereoselective. Determination of the relative configuration of the diol was aided by the

• carbinols afforded novel allene systems. Our study may be of help towards the total synthesis of solenopodin or klysimplexin derivatives. Keywords: conformational analysis; low valent titanium; marine natural products; pinacol coupling; ten-membered rings; Introduction Eunicellane-type diterpenoids share

β-Hydroxy sulfides and their syntheses

• Mokgethwa B. Marakalala,
• Edwin M. Mmutlane and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1668–1692, doi:10.3762/bjoc.14.143

• ranged from 67–92%, with enantioselectivities of 21–73% [41]. In 2009, Sun et al. reported heterobimetallic gallium–titanium variations of the same salen complexes as excellent catalysts for the thiolysis and selenolysis of meso-epoxides, giving the desired β-hydroxy sulfides and selenides in near

• ) with MS 4 Å. Asymmetric ring opening of meso-epoxides by p-xylenedithiol catalyzed by a (S,S)-(salen)Cr complex. Desymmetrization of meso-epoxide with thiophenol derivatives. Enantioselective ring-opening reaction of meso-epoxides with ArSH catalyzed by a C2-symmetric chiral bipyridyldiol–titanium

• complex. Enantioselective ring-opening reaction of stilbene oxides with ArSH catalyzed by a C2-symmetric chiral bipyridyldiol–titanium complex. Asymmetric desymmetrization of meso-epoxides using BINOL-based Brønsted acid catalysts. Lithium-BINOL-phosphate-catalyzed desymmetrization of meso-epoxides with

Syn-selective silicon Mukaiyama-type aldol reactions of (pentafluoro-λ⁶-sulfanyl)acetic acid esters with aldehydes

• Anna-Lena Dreier,
• Andrej V. Matsnev,
• Joseph S. Thrasher and
• Günter Haufe

Beilstein J. Org. Chem. 2018, 14, 373–380, doi:10.3762/bjoc.14.25

• aldehydes. While our research was well underway, Ponomarenko and Röschenthaler et al. reported similar Ti(IV)-mediated aldol reactions proceeding via titanium enolates and some succeeding or competing reactions of intermediates or products [34]. Results and Discussion As a model for our investigations we

• reaction (see above), the nucleophilic attack of the silicon enolate (in our case the ketene silylacetal) at the TiCl4-activated aldehyde results in the formation of intermediate 6. Under the influence of the electron-donating substituent, the elimination of titanium oxide dichloride (Ti(O)Cl2) is favored

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• sulfoxide. Different aryl thiols were reacted with aliphatic and aromatic alkenes, showing a reasonable functional group tolerance. In 2015, the group of Greaney substituted the transition metal photocatalysts by titanium dioxide (TiO2) nanoparticles (Scheme 7) [37]. Photoexcitation of electrons to the

Recent progress in the racemic and enantioselective synthesis of monofluoroalkene-based dipeptide isosteres

• Myriam Drouin and
• Jean-François Paquin

Beilstein J. Org. Chem. 2017, 13, 2637–2658, doi:10.3762/bjoc.13.262

• [CF=CH]-Gly 9, from benzothiazolyl fluoroaminosulfones (Scheme 2) [24][25]. The Julia–Kocienski olefination of 3-alkoxypropanal 7 with phthalimido sulfone 6 afforded the corresponding monofluoroalkene 8 as a (Z):(E) mixture (54:46). Removal of the benzyl group using titanium tetrachloride gave the

Diastereoselective Mannich reactions of pseudo-C₂-symmetric glutarimide with activated imines

• Tatsuya Ishikawa,
• Tomoko Kawasaki-Takasuka,
• Toshio Kubota and
• Takashi Yamazaki

Beilstein J. Org. Chem. 2017, 13, 2473–2477, doi:10.3762/bjoc.13.244

• peaks whose sum is given in parentheses (for example, in the case of entry 3 (Table 1), four small peaks were observed in addition to the major two). It is interesting to note that MHMDS (M: Li or Na) and LDA furnished a different isomer as the major product. We have also prepared the titanium enolate

New bio-nanocomposites based on iron oxides and polysaccharides applied to oxidation and alkylation reactions

• Daily Rodríguez-Padrón,
• Alina M. Balu,
• Antonio A. Romero and
• Rafael Luque

Beilstein J. Org. Chem. 2017, 13, 1982–1993, doi:10.3762/bjoc.13.194

• with magnetic properties. Results and Discussion In the present study, we prepared and analyzed three different catalysts based on iron oxides and polysaccharides, in particular: iron oxide–polysaccharide 4 magnetic nanoparticles (Fe2O3-PS4-MNP), iron oxide–polysaccharide 4 (Fe2O3-PS4) and titanium

• ) were generally in good agreement, supporting the validity of our assumption on DMPY adsorbing selectively on Brønsted acid sites. Inductively coupled plasma–mass spectrometry (ICP–MS) The elemental composition of the TiO2-Fe2O3-PS4 material was determined by ICP–MS. The content of iron and titanium was

• 38 and 12 wt %, respectively (Table 3). These values corroborate the incorporation of titanium in the material and confirm the results obtained by XPS. Magnetic susceptibility The magnetic susceptibility of Fe2O3-PS4-MNP is consistent with the XRD data and confirms the magnetic characteristics of the

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

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

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

• during system preparation was still necessary and it speaks against a separate evolution of the system parts. In the case of fatty acid experiments [90], fatty acid vesicles were formed on/around titanium oxide particles and the irradiation of the photosensitizer powered the reduction of NAD+ to NADH

A new member of the fusaricidin family – structure elucidation and synthesis of fusaricidin E

• Marcel Reimann,
• Louis P. Sandjo,
• Luis Antelo,
• Eckhard Thines,
• Isabella Siepe and
• Till Opatz

Beilstein J. Org. Chem. 2017, 13, 1430–1438, doi:10.3762/bjoc.13.140

• hydride, followed by Fmoc-protection and ozonolysis furnished aldehyde 5 in 57% yield over three steps (Scheme 2). The homoallylic alcohol was prepared by an enantioselective Duthaler–Hafner allylation [13] with the titanium-complex 15 in high yield and 94% ee. Attempts to perform a catalytic Keck

• allylation with BINOL-titanium catalysts failed due to low conversion [14]; however, in spite of good experience with the Maruoka–Keck allylation in another total synthesis, the conversion was not satisfying in this case [15]. After protection and guanidinylation with triflylguanidine 14, the homoallylic

Mechanochemistry-assisted synthesis of hierarchical porous carbons applied as supercapacitors

• Desirée Leistenschneider,
• Nicolas Jäckel,
• Felix Hippauf,
• Volker Presser and
• Lars Borchardt

Beilstein J. Org. Chem. 2017, 13, 1332–1341, doi:10.3762/bjoc.13.130

• mechanochemical ball-milling approach, we obtained titanium(IV) citrate-based polymers, which have been processed via high temperature chlorine treatment to hierarchical porous carbons with a high specific surface area of up to 1814 m2 g−1 and well-defined pore structures. The carbons are applied as electrode

• for the synthesis of uniform metal oxide nanoparticles to synthesize a titanium(IV) citrate-based polymer [44][45]. The Pechini method is applicable to synthesize templated mesoporous carbons [46][47][48][49], but has never been utilized for a solvent-free and rapid process based on mechanochemistry

• titanium isopropoxide (TIPP) were ground with a molar ratio of 3:1:1 in a ZrO2 milling cup for 5 min. A practical indicator for a successful mechanochemical reaction is a color change. The white and colorless educts turn to a yellow polymer with a honey-like texture. We first characterized the

Continuous-flow processes for the catalytic partial hydrogenation reaction of alkynes

• Carmen Moreno-Marrodan,
• Francesca Liguori and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2017, 13, 734–754, doi:10.3762/bjoc.13.73

• -dimethylammonium dihydrogen phosphate (HHDMA), commercially available under the name NanoSelectTM [120]. Low-content, colloidal HHDMA-palladium catalysts onto on activated carbon (Table 1, entry 3) or titanium silicate (Table 1, entry 4) provided selectivities for 1a of 97% and 96% respectively. As expected, “bare

Fast and efficient synthesis of microporous polymer nanomembranes via light-induced click reaction

• Qi An,
• Youssef Hassan,
• Xiaotong Yan,
• Peter Krolla-Sidenstein,
• Tawheed Mohammed,
• Mathias Lang,
• Stefan Bräse and
• Manuel Tsotsalas

Beilstein J. Org. Chem. 2017, 13, 558–563, doi:10.3762/bjoc.13.54

• ) wafer, coated with 5 nm titanium and 100 nm gold (Au/Ti/Si). The substrates were obtained from Georg-Albert-PVD, Germany and stored under an argon atmosphere prior to use. Infrared reflection absorption spectroscopy (IRRAS): The IRRA-spectra were recorded on a Bruker Vertex 80 purged with dried air. The

Adsorption of RNA on mineral surfaces and mineral precipitates

• Elisa Biondi,
• Yoshihiro Furukawa,
• Jun Kawai and
• Steven A. Benner

Beilstein J. Org. Chem. 2017, 13, 393–404, doi:10.3762/bjoc.13.42

• osmium phosphate, neither of which has been reported in mineralogy. Likewise, horizontal comparisons across the Periodic Table are problematic, even within transition metals. For example, we found that RNA binds to natural titanium dioxide (rutile, 21% in our experiments) and iron(III) oxide (Fe2O3

3D printed fluidics with embedded analytic functionality for automated reaction optimisation

• Andrew J. Capel,
• Andrew Wright,
• Matthew J. Harding,
• George W. Weaver,
• Yuqi Li,
• Russell A. Harris,
• Steve Edmondson,
• Ruth D. Goodridge and
• Steven D. R. Christie

Beilstein J. Org. Chem. 2017, 13, 111–119, doi:10.3762/bjoc.13.14

• -power energy source, typically a laser, to selectively melt a powder bed into a single solid body [17]. SLM can manufacture parts in a range of chemically inert and thermally stable metals such as stainless steel [18], aluminium and titanium [19][20], and is therefore an attractive technique for a

• continuous cylindrical channel running throughout (channel diameter = 2 mm, channel length = 3200 mm, theoretical reaction volume = 10 mL). The titanium alloy used to manufacture the part is thermally stable across a substantial temperature range, and chemically compatible with a wide range of organic

Stabilization of nanosized titanium dioxide by cyclodextrin polymers and its photocatalytic effect on the degradation of wastewater pollutants

• Tamás Zoltán Agócs,
• István Puskás,
• Erzsébet Varga,
• Mónika Molnár and
• Éva Fenyvesi

Beilstein J. Org. Chem. 2016, 12, 2873–2882, doi:10.3762/bjoc.12.286

• nanosized titanium dioxide (nanoTiO2) applied in photodegradation-based procedures can be stabilized with cyclodextrins in order to obtain a new, more efficient photocatalyst for the purification of waters polluted by xenobiotics applying UV irradiation. During our work, on the one hand, we studied the

• decomposition [27][28]. Recently, various photocatalysts modified by CDs have been described. For instance, reduced graphene oxide/β-CD/titanium dioxide showed enhanced removal of phenol and Cr(VI) [29], graphene nanosheets with self-assembled nanolayer of TiO2 stabilized by β-CD resulted in improved

• photodegradation of methylene blue [24], and CD-functionalized Fe3O4/TiO2 was efficient catalyst in photodecomposition of endocrine disrupting compounds, such as bisphenol A and dibutyl phthalate [30]. Producing strong oxidizing radicals (hydroxyl and superoxide radical ions) titanium dioxide is a widely used

Catalytic Wittig and aza-Wittig reactions

• Zhiqi Lao and
• Patrick H. Toy

Beilstein J. Org. Chem. 2016, 12, 2577–2587, doi:10.3762/bjoc.12.253

• via intermediate iminophosphoranes 70, using the combination of titanium tetraisopropoxide and tetramethyldisiloxane (TMDS) for the in situ reduction of byproduct 2 (Scheme 18) [36]. This group has more recently studied catalytic aza-Wittig reactions using carboxylic acid anhydrides as the starting