Enolates ambushed – asymmetric tandem conjugate addition and subsequent enolate trapping with conventional and less traditional electrophiles

• Péter Kisszékelyi and
• Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 593–634, doi:10.3762/bjoc.19.44

• all possess helpful and, to an extent, specific reactivity characteristics. Interesting boron and silicon enolates can be generated by asymmetric conjugate boration [16], or silylation [17]. From several potentially catalytically active transition metals, copper combines beneficial properties for both

C3-Alkylation of furfural derivatives by continuous flow homogeneous catalysis

• Grédy Kiala Kinkutu,
• Catherine Louis,
• Myriam Roy,
• Juliette Blanchard and
• Julie Oble

Beilstein J. Org. Chem. 2023, 19, 582–592, doi:10.3762/bjoc.19.43

• with good productivity. Alkenes without silicon in the vinyl position seemed much less reactive, such as a vinylacetal, a hindered olefin (3,3-dimethyl-1-butene), or styrene. In these cases, functionalized furfurals were not isolated. In contrast, norbornene, which has a more reactive double bond due

Catalytic aza-Nazarov cyclization reactions to access α-methylene-γ-lactam heterocycles

• Bilge Banu Yagci,
• Selin Ezgi Donmez,
• Onur Şahin and
• Yunus Emre Türkmen

Beilstein J. Org. Chem. 2023, 19, 66–77, doi:10.3762/bjoc.19.6

• analysis of lactam 19l. In order to shed light on the details of the reaction mechanism, we have performed carefully designed mechanistic studies which consist of experiments on the effect of β-silicon stabilization, the alkene geometry of the α,β-unsaturated acyl chloride reactants, and adventitious water

• on the success of the catalytic aza-Nazarov reaction. Keywords: α-methylene-γ-lactam; aza-Nazarov reaction; β-silicon effect; heterocycles; intramolecular cyclization; Introduction The rapid construction of aliphatic heterocycles from acyclic building blocks via cyclization or cycloaddition

• ) group via the β-silicon stabilization effect [36][37][38] as supported by computational studies [35]. The desilylation of intermediate 9 with the chloride of another molecule of 8 would result in the formation of final aza-Nazarov product 7 along with TMSCl (Scheme 1d). Five-membered nitrogen

Inclusion complexes of the steroid hormones 17β-estradiol and progesterone with β- and γ-cyclodextrin hosts: syntheses, X-ray structures, thermal analyses and API solubility enhancements

• Alexios I. Vicatos,
• Zakiena Hoossen and
• Mino R. Caira

Beilstein J. Org. Chem. 2022, 18, 1749–1762, doi:10.3762/bjoc.18.184

• radiation (λ = 1.5406 Å) with the X-ray generator set at 30 kV and 10 mA. All samples were lightly ground (to minimise the effects of preferred orientation) and placed on a silicon zero-background sample holder. The scanning range was 4o – 40o 2θ with a step size of 0.0164o and a primary beam path slit of

Modular synthesis of 2-furyl carbinols from 3-benzyldimethylsilylfurfural platforms relying on oxygen-assisted C–Si bond functionalization

• Sebastien Curpanen,
• Per Reichert,
• Gabriele Lupidi,
• Giovanni Poli,
• Julie Oble and
• Alejandro Perez-Luna

Beilstein J. Org. Chem. 2022, 18, 1256–1263, doi:10.3762/bjoc.18.131

• carbinols from renewable feedstock. Keywords: biomass; copper; cyclic siloxanes; 2-furyl carbinols; silicon; Introduction Progress towards the use of nonedible renewable feedstock to replace fossil resources as starting material for high-value chemicals is an important endeavor of modern synthesis [1][2

• of electrophiles to deliver product D, resulting from the overall C2–Si functionalization (Scheme 3, top) [24][25]. The key to the viability of this process is the formation of pentavalent silicon intermediate B. This suggested that a related pentavalent intermediate F could be similarly accessible

• of benzaldehyde led to the formation of adduct 14 (in 75% yield), which arose from the addition of a benzyl carbanion 17 to benzaldehyde. The generation of such a nucleophile strongly suggests the formation of pentavalent silicon intermediate 15 [27], which then produced a (stabilized) benzylic

Electrochemical formal homocoupling of sec-alcohols

• Kosuke Yamamoto,
• Kazuhisa Arita,
• Masashi Shiota,
• Masami Kuriyama and
• Osamu Onomura

Beilstein J. Org. Chem. 2022, 18, 1062–1069, doi:10.3762/bjoc.18.108

• catalytic amount of transition-metal reductants have been developed, but stoichiometric silicon electrophiles and co-reductants such as Zn were commonly required to complete the catalytic cycle [14]. More recently, visible light-mediated pinacol coupling reactions have been disclosed by several groups [15

Thiophene/selenophene-based S-shaped double helicenes: regioselective synthesis and structures

• Mengjie Wang,
• Lanping Dang,
• Wan Xu,
• Zhiying Ma,
• Liuliu Shao,
• Guangxia Wang,
• Chunli Li and
• Hua Wang

Beilstein J. Org. Chem. 2022, 18, 809–817, doi:10.3762/bjoc.18.81

• thiahelicene, a class of typical heterohelicenes, has led to the preparation of symmetric thiophene-based [5]-, [7]-, [9]-, and [11]helicenes [9][10][11][12][13][14][15][16], unsymmetric thiophene-based [7]helicenes [17], and thiophene-based double helicenes with spiro-silicon atoms [18], “saddle” formed 8π

• and DH-1–3. Molecular structures and side view for DH-1 and DH-2. A and B are molecular structures for DH-1 and DH-2. C and D are side views for DH-1 and DH-2. Carbon, sulfur, selenium, and silicon atoms are depicted with thermal ellipsoids set at the 30% probability level and all hydrogen atoms are

Inductive heating and flow chemistry – a perfect synergy of emerging enabling technologies

• Conrad Kuhwald,
• Sibel Türkhan and
• Andreas Kirschning

Beilstein J. Org. Chem. 2022, 18, 688–706, doi:10.3762/bjoc.18.70

• application for heating large metallic objects and workpieces. It is used for bending tubes, bonding, welding, sintering, and annealing of metals and alloys [11]. In addition to steel and alloys, glass or silicon are also heated or melted under inductive heating conditions [12]. In the last decade, inductive

• enable rapid heating of inductive materials such as steel or copper, or fixed-bed materials composed of steel beads as well as superparamagnetic nanoparticles in an oscillating electromagnetic field. Kirschning and co-workers introduced nanostructured particles based on Fe2O3/Fe3O4 coated with silicon

• consisting of O-allylation and Claisen rearrangement for the continuous synthesis of 2-allyl-4,6-difluorophenol (SiC = silicon carbide) [52]. Continuous flow reactions and comparison with batch reaction (oil bath). A. Pd-catalyzed transfer hydrogenations using ethanol in cyclohexene [53], B. multicomponent

Rapid gas–liquid reaction in flow. Continuous synthesis and production of cyclohexene oxide

• Kyoko Mandai,
• Tetsuya Yamamoto,
• Hiroki Mandai and
• Aiichiro Nagaki

Beilstein J. Org. Chem. 2022, 18, 660–668, doi:10.3762/bjoc.18.67

• ratio of aldehyde and oxygen to 1:9. The liquid and gas phases were combined at a T-shaped mixer with a 1 mm inner diameter and flowed through a stainless-steel tube reactor immersed in heated silicon oil for reaction temperature control. The inner pressure was maintained at 0.9 MPa using a back

Synthesis of piperidine and pyrrolidine derivatives by electroreductive cyclization of imine with terminal dihaloalkanes in a flow microreactor

• Yuki Naito,
• Naoki Shida and
• Mahito Atobe

Beilstein J. Org. Chem. 2022, 18, 350–359, doi:10.3762/bjoc.18.39

• commercial sources. 3a, 3b, and 3c were synthesized according to reported procedures (see Supporting Information File 1). A silicon oil bath was used as a heat source for the synthesis of 3a. Flow electrolysis was conducted with an in-house-built electrochemical flow microreactor. The substrate solution was

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

• variety of electron-donating and electron-withdrawing groups, though bulky silanes 92 afforded the products in reduced yield. The reaction proceeds through the formation of a silicon-centered radical generated via a Fe redox cycle (vide supra). Sequential attack on the alkenyl π-system followed by radical

• various nucleophiles 108 (Scheme 22) [105]. This protocol offers an expedient approach to 1-amino-2-silylalkanes, a classically difficult framework to synthesize, typically requiring harsh reaction conditions, multistep synthetic routes, or the use of expensive silicon reagents [106]. Moreover, the

• yield. After the prototypical homolysis of the peroxide in the presence of the Fe(II) catalyst, a silicon-centered radical 110 is formed via hydrogen abstraction. The addition of radical 110 across the alkene generates the alkyl radical intermediate 111. Oxidation of 111 by Fe(III)Ot-Bu delivers the

Solvent-free synthesis of enantioenriched β-silyl nitroalkanes under organocatalytic conditions

• Akhil K. Dubey and
• Raghunath Chowdhury

Beilstein J. Org. Chem. 2021, 17, 2642–2649, doi:10.3762/bjoc.17.177

• catalyst VIII led to ent-4 in 25% yield and 95% ee (Scheme 4). This observation confirmed that the presence of the β-silyl group in the enones played a key role in the high reactivity under the optimized reaction conditions. The stereochemistry of the silicon-substituted chiral center in compound ent-3k

Constrained thermoresponsive polymers – new insights into fundamentals and applications

• Patricia Flemming,
• Alexander S. Münch,
• Andreas Fery and
• Petra Uhlmann

Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138

Catalyzed and uncatalyzed procedures for the syntheses of isomeric covalent multi-indolyl hetero non-metallides: an account

• Ranadeep Talukdar

Beilstein J. Org. Chem. 2021, 17, 2102–2122, doi:10.3762/bjoc.17.137

• , nitrogen, oxygen, silicon, phosphorus, sulfur, selenium, and tellurium. This review will skip the reports on the corresponding carbon-centered analogs. Boranes First discovered in 1894 [34], 2,2’-bisarylborinates are used for treating prostate cancers utilizing their property of inhibiting the transient

• broad applications in organic electroluminescent devices [44]. Silanes Heteroaryl compounds containing silicon, an earth abundant and non-toxic element, are important in organic electronics or photonics and in the field of drug discovery and nuclear medicine [45][46][47][48][49][50]. The first property

• could be attributed to the facile orbital interactions of the σ* orbital of silicon and the π* orbital of the butadiene unit, which overall lowers the energy of the LUMO [51][52]. Known previously with expensive transition-metal catalyst (Ru) [53], Grubbs demonstrated the first KOt-Bu-catalyzed C2–H

An initiator- and catalyst-free hydrogel coating process for 3D printed medical-grade poly(ε-caprolactone)

• Jochen Löblein,
• Thomas Lorson,
• Miriam Komma,
• Tobias Kielholz,
• Maike Windbergs,
• Paul D. Dalton and
• Robert Luxenhofer

Beilstein J. Org. Chem. 2021, 17, 2095–2101, doi:10.3762/bjoc.17.136

• and many other substrates including ultra-nanocrystalline diamond, graphene and silicon carbide [22][23][24][25][26][27][28][29][30]. Even bottle-brush brushes could be prepared via SIPGP on various substrates for different applications [31][32][33]. Results and Discussion Here, we introduce SIPGP for

Preparation of mono-substituted malonic acid half oxyesters (SMAHOs)

• Tania Xavier,
• Sylvie Condon,
• Christophe Pichon,
• Erwan Le Gall and
• Marc Presset

Beilstein J. Org. Chem. 2021, 17, 2085–2094, doi:10.3762/bjoc.17.135

• methodology, as illustrated by the preparation of the cyano- (4bn), boron- (4ao), or silicon- (4ap) substituted SMAHOs. The efficiency of the saponification step was also illustrated by the case of α-halomalonates 3aq and 3br. Upon application of the above-mentioned conditions, the useful reagents 4aq and 4br

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

Recent advances in the application of isoindigo derivatives in materials chemistry

• Andrei V. Bogdanov and
• Vladimir F. Mironov

Beilstein J. Org. Chem. 2021, 17, 1533–1564, doi:10.3762/bjoc.17.111

• silicon nanoparticles coated with a carbon shell (Si@C) for lithium ion batteries [115]. The specific capacity of a battery designed using polyisoindigo 67 (up to 1400 mA⋅h/g) with high stability (up to 500 cycles) indicates a high potential of such structures in the search for alternatives to the

Free-radical cyclization approach to polyheterocycles containing pyrrole and pyridine rings

• Ivan P. Mosiagin,
• Olesya A. Tomashenko,
• Dar’ya V. Spiridonova,
• Mikhail S. Novikov,
• Sergey P. Tunik and
• Alexander F. Khlebnikov

Beilstein J. Org. Chem. 2021, 17, 1490–1498, doi:10.3762/bjoc.17.105

• in materials science, especially in post-silicon electronics [1][2][3][4]. Though the remarkable progress in the synthesis of the polycyclic heteroarenes during the last two decades, further development of the existing methodologies is still required for broadening of the scope of polycyclic

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

• employs silicon-glass and tubular reactors packed with nanoparticle supported catalysts. The apparatus allows the desired material to be prepared in 48% yield. The authors pointed out better outcomes were obtained in batch using a MgO-based catalyst, whose usage proved troublesome in flow due to clogging

Metal-free glycosylation with glycosyl fluorides in liquid SO₂

• Krista Gulbe,
• Jevgeņija Lugiņina,
• Edijs Jansons,
• Artis Kinens and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 964–976, doi:10.3762/bjoc.17.78

• observed when additives containing a fluorophilic silicon center were used (Table 1, entries 8 and 9). The inhibitory effect of basic molecular sieves may point to the presence and contributory role of protic acid (HF or H2SO3) in the course of the reaction [64]. Whereas, silyl additives can react with

Manganese/bipyridine-catalyzed non-directed C(sp³)–H bromination using NBS and TMSN₃

• Kumar Sneh,
• Takeru Torigoe and
• Yoichiro Kuninobu

Beilstein J. Org. Chem. 2021, 17, 885–890, doi:10.3762/bjoc.17.74

• variety of functionalities, such as boron-, silicon-, nitrogen-, and oxygen-based functional groups, and in C−C bond forming reactions, such as cross-coupling reactions [1][2][3][4][5][6]. The traditional method used for the preparation of alkyl bromides is the reaction of their corresponding alkyl

Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects

• Shivani Gulati,
• Stephy Elza John and
• Nagula Shankaraiah

Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71

• , multimode microwave reactors for parallel synthesis and multimode microwave reactors for single-batch scale-up. The reactors vary in capacity and the distribution mode of the electromagnetic wave in the reactor vessel. The introduction of the Si–C (silicon–carbon) vials enables high temperature resistance

Valorisation of plastic waste via metal-catalysed depolymerisation

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

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

• reaction conditions, PLA could be converted to the corresponding silyl ether in 92% yield, propane and silicon byproducts (8%) using the above mentioned Brookhart pincer complex [Ir(POCOP)H(THF)][B(C6F5)4] shown in Scheme 3, an excess of Et3SiH and chlorobenzene solvent at 90 °C (Scheme 13) [193]. The use

• of 6 equiv of 1,1,3,3-tetramethyldisiloxane (TMDS) led to the total conversion to propane and polydimethylsiloxane (PDMS), a silicon oil with several applications (lubricants, food-additives, breast implants). 3.2.3 Other polyesters: The hydrogenolysis reaction of esters other than PET and PLA was

A new and efficient methodology for olefin epoxidation catalyzed by supported cobalt nanoparticles

• Lucía Rossi-Fernández,
• Viviana Dorn and
• Gabriel Radivoy

Beilstein J. Org. Chem. 2021, 17, 519–526, doi:10.3762/bjoc.17.46

• catalyst (10 mg) and TBHP (63 μL of an 80 wt % solution in water, 0.5 mmol) in acetonitrile (5 mL), the corresponding alkene (0.5 mmol) was added. The reaction flask was sealed with a screw cap and introduced in a preheated silicon oil bath at a temperature high enough to ensure the reflux of the solvent