Silylenes,Silenes, and Disilenes: Novel Silicon‐Based Reagents for Organic Synthesis?

Silylenes, silenes, and disilenes are silicon analogues of carbenes and alkenes. Since the first detection and isolation of these species a few decades ago, focus has been given to their fundamental structure and reactivity properties. Recent developments show that the time is set to exploit their unique chemistry in applied areas. Emerging applications in catalysis and stereoselective synthesis point to a new field within synthetic organosilicon chemistry.     

Ionic Liquids: New Perspectives for Inorganic Synthesis?

Ionic liquids are credited with a number of unusual properties. These include a low vapor pressure, a wide liquid‐phase range, weakly coordinating properties, and a high thermal/chemical stability. These properties are certainly of great interest for inorganic synthesis and the creation of novel inorganic compounds. On the other hand, the synthesis repertoire for preparing inorganic compounds has always been broad, ranging from syntheses in solutions and melts to solid‐state reactions, and from crystal growth in the gas phase to high‐pressure syntheses. What new aspects can ionic liquids then add to the synthesis of inorganic compounds? This Minireview uses some early examples to show that the use of ionic liquids indeed provides access to unusual inorganic compounds.     

From Disymmetric Molecules to Chiral Polymers: A New Twist for Supramolecular Synthesis?

A new branch of crystal engineering appears to have borne fruit: A noncovalently bonded network consisting of the complex illustrated as a stick model on the right is converted directly into a coordination polymer with a similar molecular architecture. The implications of the new work extend beyond the boundaries of coordination chemistry since the same strategy should work equally well in organic and organometallic systems.     

Synthesis of demethoxy-amino-substituted hypocrellins: novel photosensitizers for photodynamic therapy

Gastric cancer was one of the most common malicious diseases around the world1. Photodynamic therapy (PDT) has been applied to the treatment of gastric tumors since 1980’s and desirable results has been obtained. Hypocrellin B (HB), the natural perylenequinone pigment (PQP), was found to be new effective sensitizer in the photodynamic therapy by virtue of its photophysical, photochemical and photobiological properties2. Scheme 1. The structures of AHBDs AHBDsNevertheless, natural PQP…     

Are Allenes with Zwitterionic Character Still Allenes? Of Course!

The true ground state of 1 is a matter of debate, but for clarity and convenience the allene resonance form 1 a , is the most appropriate. The arguments for aromaticity made by Christl and Engels are shown to be incorrect.

     

Novel Zwitterionic Surfactants: Synthesis and Surface Active Properties of N-(3-Alkoxy-2-Hydroxypropyl)-N, N-Dimethyl glycine Betaines

AsanAnportantsubclassofzwitterionicsurfactants.longathylchainbetaineshavebeenintensiveI}'stUdiedbymanyresearchersowingtotheiruniquestructureandconvenienceforuseindifferentpHenvironments.1MostoftheseresearchworksweredevotedtothephysicalandchemicalpropertiesofthesesurfactantS,anddevelopingneu'surfactantsofthiskindhasbeenlessnoticed.ThiscanbeattribUedtothedifficultyofthesyntheticprocedureandtheexhaustivepurificationprocesses.1'2lnthepresentwork,weintroducehydroxrpropylgroupintoalkylbetainemolec…     

RNA: primed for packing?

How does RNA's seemingly subtle 2'-hydroxyl group contribute to its diverse biological functions? Using quantitative structure-activity relationship (QSAR) analysis, Piccirilli and colleagues find that the 2'-OH fosters van der Waals and hydrophobic interactions that play underappreciated roles in RNA structure and molecular recognition.     

Zwitterionic spirocyclic λ5 Si-silicates with two cis-1,2-diphenylethene-1,2-diolato(2–) ligands: Synthesis and structural characterization

The zwitterionic ⁵ Si-silicates bis[cis-1,2-diphenylethene-1,2-diolato(2–)](morpholiniomethyl)silicate (2) and bis[cis-1,2-diphenylethene-1,2-diolato(2–)][(2,2,6,6-tetramethylpiperidinio)methyl]silicate (3) were synthesized by various methods, including remarkableSi–C cleavage reactions with benzoin. Treatment of trimethoxy(morpholinomethyl)silane (4), dimethoxy(morpholinomethyl)phenylsilane (5), or dimethoxy(methyl)(morpholinomethyl)silane (6) with two molar equivalents of benzoin in acetonitrile yielded 2. Compound 3 was synthesized by treatment of trimethoxy[(2,2,6,6-tetramethylpiperidino)methyl]silane (7) with two molar equivalents of benzoin in 1,4-dioxane/n-pentane and was isolated as the 1,4-dioxane solvate 3 ·3/2C₄H₈O₂. Compounds 2 and 3 ·3/2C₄H₈O₂ were structurally characterized by solution and solid-state NMR spectroscopy and by single-crystal X-ray diffraction. In addition, the dynamic behavior of 3 in solution was studied by VT ¹H NMR experiments.     

N-Alkoxyl Templates for Diastereoselective Pyrrolidine Synthesis

Intramolecular cyclization of N-alkoxyl amines are studied for the stereoselective preparation of 2, 4-disubstituted pyrrolidine derivatives. Reduction of oximes under acidic conditions by NaBH3CN afforded the corresponding nucleophilic hydroxylamine derivatives,which subsequently cyclized via SN2‘ mechanism to give the desired N-alkoxyl pyrrolidines.     

Synthesis for New Azasugars from Ketosugar

Imino sugars, sometimes called azasugars, are an important class of natural and unnatural compounds that have activity to selectively inhibit glycohydrolases responsible for the cleavage of glycosidic bonds.[1,2] In azasugars, the ring oxygen is replaced by nitrogen, which can be protonated under physiological pH, thus mimicking the glycopyranosyl cation. Because of the potential chemotherapeutic applications of such compounds, lots of chemists have continuing interests in the synthesis of imino sugars, such as deoxynojirimycin (DNJ, 1,5-dideoxy-1,5-imino-D-glucitol) and miglitol derivatives.     

Single-Atom or Dual-Atom in TiO2 Nanosheet: Which is the Better Choice for Electrocatalytic Urea Synthesis?

As rising star materials, single-atom and dual-atom catalysts have been widely reported in the electro-catalysis area. To answer the key question: single-atom and dual-atom catalysts, which is better for electrocatalytic urea synthesis? we design two types of catalysts via a vacancy-anchorage strategy: single-atom Pd₁−TiO₂ and dual-atom Pd₁Cu₁−TiO₂ nanosheets. An ultrahigh urea activity of 166.67 mol_urea mol_Pd⁻¹ h¹ with the corresponding 22.54 % Faradaic efficiency at −0.5 V vs. reversible hydrogen electrode (RHE) is achieved over Pd₁Cu₁−TiO₂, which is much higher than that of Pd₁−TiO₂. Various characterization including an in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and theoretical calculations demonstrate that dual-atom Pd₁Cu₁ site in Pd₁Cu₁−TiO₂ is more favorable for producing urea, which experiences a C−N coupling pathway with a lower energy barrier compared with Pd₁ in Pd₁−TiO₂.     

Polystyrene-supported Selenomethyl-sulfonates: Efficient Reagents for Stereocontrolled Synthesis of Substituted Vinyl Sulfones

Solid-phase methodology has been rapidly and extensively applied to the preparation of small organic molecules recently1. Organic selenides are of considerable interest in academia because of their wide involvement as key intermediates in organic synthesis. However, organic selenides are highly malodorous and generally unpleasant and difficult to handle, especially because of their toxicity. Since the first organoselenium resin2 was reported in 1976, several groups have developed some organ…     

Propane Phosphonic Acid Anhydride: A Mild Reagent for β-Lactam Synthesis

The use of propane phosphonic acid anhydride (T3P) as an acid activating reagent was demonstrated in the syntheses of cis β-lactams from the reactions of a glycine Dane salt and various imines.     

Novel,Amino Acid-Derived Heterobicycles: Scaffolds for β-Turn Mimics and Targets for Combinatorial Synthesis

Interest in combinatorial synthetic design and in α-turn mimics led to the development of a short synthesis of three ring systems (1—3) from cyclization of hydroxyacyl-dipeptide aldehyde derivatives, 6—8, with trifluoroacetic acid in acetone. The bicyclic products 1 and 2 were formed as single diastereomers with the benzyl substituent in the exo orientation, as determined by X-ray crystallography; the benzo analogs 3 were formed as mixtures of epimers, with the endo isomers predominating.