A Ring Expansion Strategy in Antiviral Synthesis: A Novel Approach to TAK‐779

Abstract

A synthesis of TAK‐779 that relies on construction of a key carboxylic acid intermediate by a ring expansion with TMSCHN₂ is described.     

A Novel Method for Preparing Polyurethane Based Conductive Composites with Low Percolation Threshold

A novel method for preparing conductive carbon black filled polymer composites with low percolation threshold from polyurethane emulsion are reported in this paper. The experimental results indicate that with a rise in carbon black concentration the insulator-conductor transition in the emulsion blended composites occurs at 0.8-1.4vol%. In contrast, the solution blended composites exhibit drastic increase in conductivity at conducting filler fraction as high as 12.3-13.3vol%. It is demonstrated that the composites microstructure rather than chemical structure of the matrix polymer predominantly determines the electrical conduction performance of the composites.     

Novel Approach to 3‐Methyl‐1H‐quinoxalin‐2‐ones

A novel approach to the synthesis of 3‐methyl‐1H‐quinoxalin‐2‐ones has been described. These compounds were regioselectively prepared by starting from substituted phenylamines and α‐chloropropionyl chloride through the efficient procedures of acylation, nitration, reduction, intramolecular alkylation, and oxidation.     

L‐Proline–H2O2: A New Chemoselective Approach for Oxidation of Sulfides to Sulfoxides

A facile and selective oxidation of sulfides to sulfoxides using an L‐proline–H₂O₂ system for structurally divergent sulfide substrates with excellent yields at ambient conditions is reported.     

New Approach for the Synthesis of N‐Indolyl Ketones and Aldehydes

A new approach for the synthesis of N‐indolyl ketones and aldehydes was developed. In the reaction of N‐indolyl carboxylic acids with alkyl lithium, an interesting phenomenon appeared when using THF as solvent instead of ethyl ether.     

Synthesis of Some C‐4 Hydroxybenzo[c]pyrans: A New Approach

A new synthetic approach to the synthesis of some epimeric C‐4‐hydroxy‐benzo[c]pyrans is described. A key step in their formation is stereoisomerisation of a nonconjugated ortho alkenylphenylketone and ‐ester using palladium bisacetonitrile [bisacetonitriledichloropalladium(II)] to give the corresponding conjugated E stereoisomers which cyclize on treatment with meta‐chloroperbenzoic acid (m‐CPBA) to afford the target compounds.     

A Novel Chemo‐selective Epoxidation across Acrylate Ester: Synthesis of New Water‐Soluble Forskolin Analogues

While removing the TBDMS group from OH protection, a novel epoxidation reaction occurred across acrylate ester attached to a forskolin fragment. Besides spectroscopic data, the epoxide formation was confirmed by ring opening with a secondary amine. This unique epoxidation reaction, to our knowledge, is not known in the literature. This reaction led us to discover a simple deblocking protocol. The epoxide and the desired Michael substrates were used to introduce imidazole into forskolin.     

2‐Hydroxy‐1,2,3,6‐tetrahydro‐azulen‐6‐carboxylic Acid Ethyl Ester—A Novel Precursor for a New Class of Liquid Crystalline Materials

A novel approach for the syntheses of carbene adduct 4 is reported. A ring-enlargement strategy was employed for the synthesis of precursors 5 and 6 and established the mechanism of the formation of azulene derivative 6. Synthesis of target precursor 13, a novel precursor for the synthesis of new mesogenic materials, and its various halogenated derivatives (14–16) was carried out.     

A New Synthesis of 5,8‐Dimethyl‐2‐tetralone—A Potential Intermediate for the Synthesis of Ring‐A Aromatic Sesquiterpenes. Novel Transformation During Acetoxylation of 5,8‐Dimethyldihydronapthalene

Abstract

An efficient synthesis of 5,8‐dimethyl‐2‐tetralone 4 starting from 5,8‐dimethyl‐1‐tetralone 2 is described. It was converted into the unsaturated derivative 3, which on epoxidation followed by acid hydrolysis yielded tetralone 4. Acetoxylation of 3 with manganese(III) acetate and potassium bromide afforded dimethylnaphthalene 8 and derivative 9.     

A New Approach for Asymmetric Synthesis of （-）-Umbelactone

A concise and efficient total synthesis of (-)-umbelactone 1, an occurring γ-hydroxymethyl-α, β-butenolide from Memycelon umbelatum Burro, is described. The synthesis features the use of a ring closing metathesis strategy.     

Gelrite‐Based In Vitro Gelation Ophthalmic Drug Delivery System of Gatifloxacin

The conventional ophthalmic solutions have demonstrated poor bioavailability and low therapeutic response due to rapid precorneal elimination of drug, which could be overcome by the use of in situ gelling systems that are instilled as drops into the eye and undergo a sol‐gel transition in the cul‐de‐sac. The present work describes the formulation of an ophthalmic delivery system of an antibacterial agent, Gatifloxacin, based on the concept of ion‐activated in situ gelation; the rheological properties of the formulation and in vitro release of the drug were evaluated. Gelrite gellan gum, a novel vehicle for ophthalmic delivery system, which gels in the presence of mono/divalent cations present in the tear fluid, was used as the gelling agent. The developed formulation showed pseudoplastic rheology and was therapeutically efficacious and provides sustained release of the drug over a 12‐hour period. The developed system is thus a viable alternative to conventional eye drops.     

Glycosylated Hematoporphyrins: A New Approach in Cancer Phototherapy?

ABSTRACT

Although the phenomenon is not fully understood, it is now well established that some porphyrins have a natural tendency to concentrate more in malignant tumors than in normal tissue. This property has found an application in photodynamic therapy of cancers in which a tumor, with an enriched concentration of porphyrin, can be selectively destroyed by applying light, without damage to surrounding cells.¹     

A Novel Approach for the Surface Modification of Polymeric Membrane with Phospholipid Polymer

A new economic and convenient method to modify the surface of microporous polypropylene (PP) membranes with phospholipid polymer was given. The process included the photo-irradiated graft polymerization of N,N-dimethylaminoethyl methacrylate (DMAEMA) and the ring-opening reaction of the grafted polyDMAEMA with 2-alkyloxy-2-oxide-1,3,2-dioxo-phospholanes (AOP). Four AOPs, whose alkyloxy groups consisted of dodecyl, tetradecyl,hexadecyl and octadecyl moieties, were used to convert the grafted polyDMAEMA to phospholipidpolymers. FT-IR spectra confirmed the chemical change of membrane surface. Platelets adhesion experiment indicated that PP membrane with excellent blood compatible surface could be fabricated by this method.     

A Novel Approach for Observing Morphology of Polypropylene under Ultrasonic Vibration by SALS

In this paper, a set of ultrasonic vibration device connecting with small angle light scattering(SALS) for in-situ observing phase-transition of polymer under ultrasonic vibration was established. The experiments for verifying polypropylene(PP) indicated that ultrasonic vibration resulted in the decrease of the crystallization rate and made PP crystallizable at low temperature.     

A Novel Approach to Synthesis of Tricyclic Diterpenoid

A novel approach has been found and the first total synthesis of (±)-Salvirecognine was accomplished by using it. In which intramolecular cyclization and Friedel-Crafts alkylation took place simultaneously to afford key intermediates for synthesis of aromatic tricyclic diterpenoids OMe PPA O O O OMe 1 2 Scheme 1 As shown in Scheme 1 intramolecular cyclization and Friedel-Crafts alkylation took place simultaneously when compound 1 was treated by PPA at 125 ℃. In which the i-pr…     

RNA Methylation m6A:A New Code and Drug Target?

The m^6A-RNA modification is a dynamic and reversible process,which has emerged as a new RNA code for the regulation of gene expression.The functional network of methyltransferases(writers),demethylases(erasers),and binding proteins(readers)modulate the level of m^6A modification.Dysfunction of RNA methylation has been associated with various fundamental biological processes and human diseases.Herein,we briefly introduce an understanding-enabled manipulation on m^6A RNA modification with an emphasis on the use of small-molecule intervention.     

A New Approach to α—Bromochalcones

α-Bromo benzolymethylene triphenylphosphorane 3 has been synthesized by the reaction of benzoylmethylene triphenylphosphorane 1 with N-bromosuccinimide in the yield of 87% and can react with aromatic aldehydes 4 to give α-bromochalcones 5 in good yields.     

Janus Gold Nanostars–Mesoporous Silica Nanoparticles for NIR-Light-Triggered Drug Delivery

Janus gold nanostar–mesoporous silica nanoparticle ( AuNSt–MSNP ) nanodevices able to release an entrapped payload upon irradiation with near infrared (NIR) light were prepared and characterized. The AuNSt surface was functionalized with a thiolated photolabile molecule ( 5 ), whereas the mesoporous silica face was loaded with a model drug (doxorubicin) and capped with proton-responsive benzimidazole-β-cyclodextrin supramolecular gatekeepers ( N 1 ). Upon irradiation with NIR-light, the photolabile compound 5 photodissociated, resulting in the formation of succinic acid, which induced the opening of the gatekeeper and cargo delivery. In the overall mechanism, the gold surface acts as a photochemical transducer capable of transforming the NIR-light input into a chemical messenger (succinic acid) that opens the supramolecular nanovalve. The prepared hybrid nanoparticles were non-cytotoxic to HeLa cells, until they were irradiated with a NIR laser, which led to intracellular doxorubicin release and hyperthermia. This induced a remarkable reduction in HeLa cells viability.     

Rose Oxides: A Facile Chemo and Chemo‐Enzymatic Approach

Nonracemic rose oxides were synthesized from racemic or nonracemic monoterpene alcohol citronellol by a novel chemo and chemo‐enzymatic route. After the key step of bromomethoxylation of citronellol, the intermediate was dehydrobrominated by a base, followed by an acid catalyzed demethoxylation along with cyclization to furnish rose oxides in high yield. The racemic dehydrobrominated precursor was also kinetically resolved using various lipases to produce nonracemic rose oxides.