Release of Volatile Cyclopentanone Derivatives from Imidazolidin-4-One Profragrances in a Fabric Softener Application

Imidazolidin-4-ones were investigated as hydrolytically cleavable profragrances to increase the long-lastingness of perfume perception in a fabric softener application. The reaction of different amino acid amides with 2-alkyl- or 2-alkenylcyclopentanones as the model fragrances to be released afforded the corresponding bi- or tricyclic imidazolidin-4-ones as mixtures of diastereoisomers, which were separated by column chromatography. In polar solution, the different stereoisomers equilibrated under thermodynamic conditions to form mixtures with constant isomeric distributions, as shown by NMR spectroscopy. Dynamic headspace analysis on dry cotton demonstrated the controlled fragrance release from the precursors in practical application. Under non-equilibrium conditions (continuous evaporation of the fragrance) and depending on the structure and stereochemistry of the profragrances, the recorded headspace concentrations of the fragrance released from the precursors increased by a factor of 2 up to 100 with respect to the unmodified reference. Prolinamide-based precursors released the highest amount of fragrance and were thus found to be particularly suitable for prolonging the evaporation of cyclopentanone-derived fragrances on a dry cotton surface.     

Controlled aging of PbS colloidal quantum dots under mild conditions

A new controlled aging methodology was developed for the synthesis of PbS colloidal quantum dots (QDs), applying larger PbS QDs as a starting material for smaller QDs by application of environmentally friendly oleic acid and oleylamine as reagents. This simple and mild procedure provides a possible strategy for tailoring the size-dependent properties of PbS QDs.     

Visible-light-triggered release of nitric oxide from N-pyramidal nitrosamines

Although many organic/inorganic compounds that release nitric oxide (NO) upon photoirradiation (phototriggered caged-NOs) have been reported, their photoabsorption wavelengths mostly lie in the UV region, because X-NO bonds (X=heteroatom and metal) generally have rather strong π-bond character. Thus, it is intrinsically difficult to generate organic compounds that release NO under visible light irradiation. Herein, the structures and properties of N-pyramidal nitrosamine derivatives of 7-azabicyclo[2.2.1]heptanes that release NO under visible light irradiation are described. Bathochromic shifts of the absorptions of these nitrosamines, attributed to HOMO (n)-LUMO (π*) transitions associated with the nonplanar structure of the N-NO moiety, enable the molecules to absorb visible light, which results in N-NO bond cleavage. Thus, these compounds are innate organic caged-NOs that are uncaged by visible light.     

The destruction of organic pollutants under mild reaction conditions: A review

A survey of the literature covering the destruction of organic pollutants accomplished under mild reaction conditions is presented. Technologies presented are segregated according to two main reaction pathways; oxidation and reduction. Sub-topics discussed are representative of the main component of the degradation system, including the following; electrochemical reactors, hydrogen as a reducing agent, zero-valent metals, biological based systems, photolytic processes, Fenton reaction, and a recently discovered process that is a form of room temperature and pressure oxygen activation.     

Controlled release of Ibuprofen from dealuminated faujasites

Four dealuminated faujasite samples have been employed as matrices for Ibuprofen adsorption and in vitro drug delivery with the aim of adapting the pore size to the size of the drug molecule and to study the influence of Al content upon the drug delivery. Ca. 15 wt% of Ibuprofen is adsorbed in the zeolite cavities. FTIR shows that the zeolite hydroxyl groups interact with Ibuprofen and, in addition, carboxylate species bonded to extraframework Al species are detected in the most dealuminated samples. Two stages are observed in the Ibuprofen delivery. In the first hours, the release is governed by a diffusion process, showing a similar delivery rate independently of the Al content. However, after this stage, the Al content is determinant in drug delivery, being the release faster when the framework Si/Al ratio increases up to 22, and then decreases for Si/Al=62. The behaviour of the highly dealuminated material is probably due to the predominance of Van der Waals interaction between the drug and the siliceous zeolite framework.     

Iridium-catalyzed isomerization of primary allylic alcohols under mild reaction conditions

The isomerization of primary allylic alcohols into the corresponding aldehydes has been accomplished using an analogue of Crabtree’s iridium hydrogenation catalyst and by adequately tuning the experimental conditions. A wide range of substrates is converted quantitatively into the desired aldehyde at room temperature in expedient reaction times by using catalyst loading as low as 0.25 mol %.     

Spectroscopic response of ferrocene derivatives bearing a BODIPY moiety to water: a new dissociation reaction

Ferrocence and its derivatives have long been known to be a class of stable organometallic compounds, and their dissociation usually occurs under harsh conditions. Here we report a new type of ferrocene derivatives, 4,4-difluoro-8-ferrocenyl-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene and 4,4-difluoro-2,6-diethyl-8-ferrocenyl-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene, which surprisingly can hydrolyze under mild conditions. These two derivatives, initially developed as donor-acceptor probes for reactive oxygen species by incorporating the electron donor of ferrocene as a quencher into the fluorophore of BODIPY (boron dipyrromethene difluoride), barely emit fluorescence. Upon reaction with H(2)O under the irradiation of natural light at room temperature, however, both of the probes display a dramatic color change and fluorescence retrievement. Detailed experimental results reveal that the reaction of the probes with H(2)O leads to the removal of a cyclopentadiene unit and iron(II), yielding a BODIPY derivative that retains the other cyclopentadiene unit and shows a large fluorescence enhancement (over 100-fold). Moreover, the increase in fluorescence intensity is directly proportional to microamount of water, and the presence of both light and H(2)O is indispensable in the reaction, which makes the present system of great potential not only for determining water but also for forming a AND logic gate. Most importantly, the present mild dissociation reaction may give a new insight into the stability of ferrocene and its derivatives.     

Controlled Release from and Tissue Response to Physically Bonded Hydrogel Nanoparticle Assembly

Our recent work on synthesis and application of thermally gelling nanoparticle dispersions is briefly reviewed here. These nanoparticles consist of interpenetrating polymer networks (IPN) of poly-acrylic acid (PAAc) and poly(N-isopropylacrylamide) (PNIPAM). The aqueous IPN nanoparticle dispersions with polymer concentrations above 2.5 wt % underwent an inverse thermoreversible gelation at about 33 °C. Dextran markers of various molecular weights as model macromolecular pseudodrugs were mixed with the IPN nanoparticle dispersion at room temperature. At body temperature, the dispersion became a gel. The dextran release profiles were then measured using UV-visible spectroscopy. The biocompatibility of this nanoparticle assembly was assessed using an animal implantation model.     

Copper-catalyzed alkyne-aryne coupling reaction under microwave conditions: preparation of unsymmetric and symmetric di-substituted alkynes

Several unsymmetric and symmetric alkynes were prepared excellent to modest yields by generating benzyne from the reaction of 2-(trimethylsilyl)phenyl triflate with CsF in the presence of CuI and terminal alkyne under microwave heating for 30 min at 150 °C. Using conventional heating, the reactions required 24 h reaction time.     

Iron-promoted C-C bond cleavage of 1,3-diketones: a route to 1,2-diketones under mild reaction conditions

A conceptual method for the preparation of 1,2-diketones is reported. The selective C-C bond cleavage of 1,3-diketones affords the 1,2-diketones in high yields under mild reaction conditions in air by the use of FeCl(3) as the catalyst and tert-butyl nitrite (TBN) as the oxidant without the use of solvent. The possible reaction mechanism is discussed. This protocol provides an expeditious route to the useful 1,2-diketones.     

Hydrothermal treatment of microcrystalline cellulose under mild conditions: characterization of solid and liquid-phase products

Microcrystalline cellulose (MCC) particles were subjected to hydrothermal treatment using an autoclave with temperatures ranging from 200 to 250 °C and reaction times ranging from 20 to 100 min. The structure and chemical composition of the reacted solid phase was analyzed by X-ray diffraction, thermo-gravimetric analysis, FTIR spectroscopy and ¹³C-NMR spectroscopy. The relative composition of the water-soluble products was determined by one-dimensional ¹H-NMR and two-dimensional homo and hetero-nuclear NMR spectroscopy. Within the experimental temperature and treatment time ranges, the crystallinity of the reacted solid phase was found to be mostly dependent on the treatment temperature while the aqueous solution was found to change with both temperature and treatment time. At the maximum temperature employed in this study (250 °C), the solid products are similar to amorphous oxidized carbon with glucose as the main water-soluble product. At lower temperatures the particles are unconverted MCC and the liquid products are primarily levulinic acid, formic acid and acetic acid with smaller quantities of 5-hydroxymethyl-furfural and glucose. Heterogeneous and liquid phase reaction-schemes are proposed to explain the observed solid and water-soluble products as a function of temperature and treatment time.     

Efficient nitro-aldol reaction using SmI2: a new route to nitro alcohols under very mild conditions

A novel method to obtain racemic 1-nitroalkan-2-ols by reaction of bromonitromethane with a variety of aldehydes and promoted by SmI2 is reported. On the basis of these results, the chiral version has also been performed with chiral N,N-dibenzyl amino aldehydes, affording the corresponding enantiopure 3-amino-1-nitroalkan-2-ols with good stereoselectivity.     

A convenient access to 2,4-disubstituted quinazolines via one-pot three-component reaction under mild conditions†

Abstract

A new and practical method has been developed for the synthesis of 2,4-disubstituted quinolines via one-pot three-component reaction of o-amino arylketones, aldehydes and ammonium acetate in high yields by using DDQ in CH₃CN under mild conditions. Neutral conditions, atom economy, easy work-up procedures and compatible with different functional groups are the salient features of this protocol.     

Ionic liquid mediated Cu-catalyzed cascade oxa-Michael-oxidation: efficient synthesis of flavones under mild reaction conditions

Flavonoids are a class of natural products, found in a wide range of vascular plants and dietary components. Their low toxicity and extensive biological activities, including anti-cancer and anti-bacterial, have made them attractive candidates to serve as therapeutic agents for many diseases. Herein, we disclose a highly efficient synthetic method of CuI-catalyzed cascade oxa-Michael-oxidation, using chalcones as substrates, mediated by the ionic liquid [bmim][NTf2] at a low temperature. This efficient synthetic method has demonstrated high synthetic utility and can afford flavones in good to high yields (up to 98%).     

Synthesis of ene-allenes via palladium-catalyzed hydride-transfer reaction of propargylic amines under mild conditions

The palladium-catalyzed allene transformation reaction from propargylic amines proceeded in the presence of Pd₂(dba)₃·CHCl₃ (5 mol %) and (C₆F₅)₂PC₂H₄P(C₆F₅)₂ (10 mol %) in CHCl₃ at room temperature to give the corresponding allenes in good to high yields. Dicyclohexyl groups substituted on the nitrogen of propargylic amines were found to be effective for the current transformation and the conjugated ene-allenes 4 were synthesized from the corresponding propargylic amines 3 under mild conditions.     

Simple enzyme reactors suitable for the byproduct-free preparation of the aglycones of naturally occurring glycosides under mild conditions

Naringinase from Penicillium species—containing α-l-rhamnosidase and β-d-glucosidase activity—immobilized on silicate carriers can be used as a mild and effective means to cleave naturally occurring glycosides into their aglycones and sugar components. The procedure was tested with flavonoid-, anthraquinone-, and steroidglycosides. Since the solubility of such compounds is limited in aqueous solutions, a simple batch procedure has been developed to convert solid substrates suspended in only small amounts of buffer to the desired products with high yields.     

Preparation and characterization of HypoGel-supported Pd nanocatalysts for Suzuki reaction under mild conditions

A new heterogeneous catalyst composed of Pd nanoparticles immobilized within a HypoGel resin has been prepared in the absence of any ligands using an extensive cross-linking method. This new-ly develop...