An efficient synthesis of (±)-frondosin B using a Stille–Heck reaction sequence

A concise, convergent synthesis of (±)-frondosin B has been developed based on the application of a Stille–Heck reaction sequence of 2-chloro-5-methoxybenzo[b]furan-3-yl triflate and 2-(3-butenyl)-3-(trimethylstannyl)cyclohex-2-enone giving the racemic natural product in a 34% overall yield.

Fast, energy-efficient synthesis of luminescent carbon quantum dots

A simple, fast, energy and labour efficient, carbon dot synthesis method involving only the mixing of a saccharide and base is presented. Uniform, green luminescent carbon dots with an average size of 3.5 nm were obtained, without the need for additional energy input or external heating. Detection of formation moment for fructose-NaOH-produced carbon dots is also presented.

Isoselenocyanates derived from Boc/Z-amino acids: synthesis, isolation,characterization, and application to the efficient synthesis of unsymmetrical selenoureas and selenoureidopeptidomimetics

Isoselenocyanates derived from Boc/Z-amino acids are prepared by the reaction of the corresponding isonitriles with selenium powder in presence of triethylamine at reflux. The utility of these new classes of isoselenocyanates in the preparation of selenoureidodipeptidomimetics possessing both amino as well as carboxy termini has been accomplished. The H-1 NMR analysis confirmed that the protocol involving the conversion of isonitriles to isoselenocyanates and their use as coupling agents in assembling selenour-eido derivatives is free from racemization. (C) 2010 Elsevier Ltd. All rights reserved.

A facile entry to macrocyclic disulfides: an efficient synthesis of redox-switched crown ethers

An interesting sulfur transfer reaction with benzyltriethylammonium tetrathiomolybdate has been used efficiently for the synthesis of macrocyclic disulfides. This methodology has been extended to a high-yield synthesis of ''redox-switched'' crown ethers which have potential application for selective ion transport across liquid membranes.

Efficient synthesis of carbonyl compounds: oxidation of azides and alcohols catalyzed by vanadium pentoxide in water using tert-butylhydroperoxide

Catalytic amount of vanadium reagent with tert-butylhydroperoxide as the oxidant was found to be an excellent oxidizing agent in aqueous medium. Vanadium pentoxide with aq tert-butylhydroperoxide readily oxidizes primary benzylic azides to the corresponding acids and secondary benzylic azides to the corresponding ketones in excellent yields. Further, vanadium pentoxide and aq tert-butylhydroperoxide combination turned out to be an effective catalyst for the oxidation of alcohols. Using vanadium pentoxide and aq tert-butylhydroperoxide primary alcohols were oxidized to the corresponding acids, whereas secondary alcohols underwent a smooth transformation to furnish corresponding ketones in excellent yields. All the oxidations are performed in water. (C) 2011 Elsevier Ltd. All rights reserved.

Energy-efficient synthesis of ferrite powders and films

In recent years, there has been significant effort in the synthesis of nanocrystalline spinel ferrites due to their unique properties. Among them, zinc ferrite has been widely investigated for countless applications. As traditional ferrite synthesis methods are energy- and time-intensive, there is need for a resource-effective process that can prepare ferrites quickly and efficiently without compromising material quality. We report on a novel microwave-assisted soft-chemical synthesis technique in the liquid medium for synthesis of ZnFe2O4 powder below 100 °C, within 5 min. The use of β-diketonate precursors, featuring direct metal-to-oxygen bonds in their molecular structure, not only reduces process temperature and duration sharply, but also leads to water-soluble and non-toxic by-products. As synthesized powder is annealed at 300 °C for 2 hrs in a conventional anneal (CA) schedule. An alternative procedure, a 2-min rapid anneal at 300 °C (RA) is shown to be sufficient to crystallize the ferrite particles, which show a saturation magnetization (MS) of 38 emu/g, compared with 39 emu/g for a 2-hr CA. This signifies that our process is efficient enough to reduce energy consumption by ∼85% just by altering the anneal scheme. Recognizing the criticality of anneal process to the energy budget, a more energy-efficient variation of the reaction process was developed, which obviates the need for post-synthesis annealing altogether. It is shown that the process also can be employed to deposit crystalline thin films of ferrites.

Efficient Synthesis of Single-Chain Polymer Nanoparticles via Amide Formation

Single-chain technology (SCT) allows the transformation of individual polymer chains to folded/collapsed unimolecular soft nanoparticles. In this work we contribute to the enlargement of the SCT toolbox by demonstrating the efficient synthesis of single-chain polymer nanoparticles (SCNPs) via intrachain amide formation. In particular, we exploit cross-linking between active methylene groups and isocyanate moieties as powerful "click" chemistry driving force for SCNP construction. By employing poly(methyl methacrylate)- (PMMA-) based copolymers bearing beta-ketoester units distributed randomly along the copolymer chains and bifunctional isocyanate cross-linkers, SCNPs were successfully synthesized at r.t. under appropriate reaction conditions. Characterization of the resulting SCNPs was carried out by means of a combination of techniques including size exclusion chromatography (SEC), infrared (IR) spectroscopy, proton nuclear magnetic resonance (H-1 NMR) spectroscopy, dynamic light scattering (DLS), and elemental analysis (EA).

Efficient synthesis and utilization of phenyl-substituted heteroaromatic carboxylic acids as aryl diketo acid isosteres in the design of novel HIV-1 integrase inhibitors

Three new types of aryl diketo acid (ADK) isosteres were designed by conversion of the biologically labile 1,3-diketo unit into heteroaromatic motif such as isoxazole, isothiazole, or 1H-pyrazole to improve the physicochemical property of ADK-based HIV-1

A Facile and Efficient Synthesis of Polyfunctionalized Pyridin-2(1H)-ones from β-Oxo Amides under Vilsmeier Conditions

A facile and efficient one-pot synthesis of polysubstituted pyridin-2(1H)-ones from a variety of beta-oxo amides under Vilsmeier conditions is described, and a mechanism involving sequential halogenation, formylation and intramolecular nucleophilic cyclization is proposed

Efficient synthesis of α-alkylidene-β-lactams via NaOH-promoted intramolecular aza-Michael addition of α-carbamoyl ketene-S,S-acetals in aqueous media

A facile and efficient synthesis of substituted alpha-alkylidene-beta-lactams have been developed via a NaOH-promoted intramolecular aza-Michael addition of alpha-carbamoyl, alpha-(1-chlorovinyl) ketene-S,S-acetals and subsequent nucleophilic vinylic substitution (SNV) reaction in alcoholic aqueous media. (C) 2008 Elsevier Ltd. All rights reserved.

Vilsmeier Reaction of Enaminones: Efficient Synthesis of Halogenated Pyridin-2(1H)-ones

A facile and efficient one-pot synthesis of halogenated pyridin-2(1H)-ones from a series of readily available enaminones under Vilsmeier conditions is described, and a mechanism involving sequential halogenation, formylation, and intramolecular nucleophilic cyclization is proposed.

Efficient synthesis of highly substituted pyrrolin-4-ones via PIFA-mediated cyclization reactions of enaminones

A convenient and efficient synthesis of highly substituted pyrrolin-4-ones is developed via the PIFA-mediated cyclization reactions of readily available enaminones, and a mechanism involving sequential cleavage of N-C bond, formation of new N-C bond, intramolecular addition reaction, and benzilic acid type rearrangement is proposed.

Efficient synthesis of substituted tetrahydrothiopyrano[2,3-b]thiopyran-4,5-diones by a double annulation strategy from dialkenoylketene dithioacetals

An efficient synthetic procedure for substituted 2,3,6,7tetrahydrothiopyrano [2,3-b] thiopyran-4,5 -diones by a double annulation strategy is described. The ring systems are made in good yields from readily available dialkenoylketene dithioacetals in the presence of either sodium sulfide nonahydrate/N,N-dimethylformamide (DMF) or a sodium hydride/DMF/amine system.