FACILE REDUCTION OF AROMATIC NITRO COMPOUNDS WITH HYDROIODIC ACID UNDER MICROWAVE IRRADIATION ON SOLID SUPPORT

Reduction of aromatic nitro compounds to amine with hydroiodic acid was revisited. Under microwave irradiation on solid support the reduction proceeded efficiently and rapidly.     

SELECTIVE OXIDATION OF BENZYLIC ALCOHOLS USING CAN SUPPORTED ONTO SILICA GEL UNDER MICROWAVE IRRADIATION

Cerium ammonium nitrate (CAN) adsorbed on HNO ₃ /silica gel is a mild reagent for selective oxidation of benzylic alcohols to the corresponding aldehydes under microwave irradiation in solventless system.     

A Preferred Intramolecular ‘Ene’ Reaction Between Ketene and Olefin

Aplysin (1), a marine sesquiterpene was isolated from ‘aplysia kurodai’ and its structure was ellucidated by Hirata-et-al¹. They also reported the synthesis of racemic aplysin². Their synthetic route involved cyclopentanone (2) as a well-characterized intermediate. We visualized the synthesis of cyclobutanone (3) and its subsequent conversion to (2) as an attractive alternative. But during our attempts to synthesize the said cyclobutanone, we have come across a very facile intramolecular ‘ene’ reaction between ketene and olefin. We report our unexpected observations in this communication.     

A Simple and Short Synthesis of Z-6-Heneicosen-11-One and Z-1,6-Heneicosen-11-One,The Sex Pheromones of Douglas-Fir Tussock Moth

Z-6-Heneicosen-11-one (1) and Z-1,6-Heneicosen-11-one (2) are the sex pheromones of the Douglas-Fir Tussock moth, ‘Orgyia Pseudo Sugata’, isolated^1,2 in 1975 and 1978 respectively. In contrast with other lepidopterous pheromones, which are unsaturated C₁₂-C₁₄ primary alcohols or acetates, these were found to be C₂₁ ketones. The Douglas-Fir Tussock moth is a severe defoliator of the Fir forest; consequently, considerable interest attends the synthesis of these two pheromones. A number of syntheses of these two pheromones have been reported3 amongst which is one of our synthesis using N,N-dimethyl acetone 4 hydrazone as key intermediate.     

Tetrameric DABCO–Bromine Complex: A Novel Reagent for Regeneration of Carbonyl Compounds From Aldoximes and Ketoximes

An efficient and convenient conversion of aldoximes and ketoximes to the corresponding carbonyl compounds with tetrameric DABCO–bromine complex is reported.     

Factors affecting the morphology of benzoyl peroxide microsponges

Benzoyl peroxide (BPO) is primarily used in the treatment of mild to moderate acne. However, its application is associated with skin irritation. It has been shown that encapsulation and controlled release of BPO could reduce the side effect while also reducing percutaneous absorption when administered to the skin. The aim of the present investigation was to design and formulate an appropriate encapsulated form of BPO, using microsponge technology, and explore the parameters affecting the morphology and other characteristics of the resultant products employing scanning electron microscopy (SEM). Benzoyl peroxide particles were prepared using an emulsion solvent diffusion method by adding an organic internal phase containing benzoyl peroxide, ethyl cellulose and dichloromethane into a stirred aqueous phase containing polyvinyl alcohol (PVA). Different concentrations of BPO microsponges were incorporated in lotion formulations and the drug release from these formulations were studied. The SEM micrographs of the BPO microsponges enabled measurement of their size and showed that they were spherical and porous. Results showed that the morphology and particle size of microsponges were affected by drug:polymer ratio, stirring rate and the amount of emulsifier used. The results obtained also showed that an increase in the ratio of drug:polymer resulted in a reduction in the release rate of BPO from the microsponges. The release data showed that the highest and the lowest release rates were obtained from lotions containing plain BPO particles and BPO microsponges with the drug:polymer ratio of 13:1, respectively. The kinetics of release study showed that the release data followed Peppas model and the main mechanism of drug release from BPO microsponges was diffusion.     

Operational risk: Emerging markets,sectors and measurement

The role of decision support systems in mitigating operational risks in firms is well established. However, there is a lack of investment in decision support systems in emerging markets, even though inadequate operational risk management is a key cause of discouraging external investment. This has also been exacerbated by insufficient understanding of operational risk in emerging markets, which can be attributed to past operational risk measurement techniques, limited studies on emerging markets and inadequate data.     

Ultrasonic accelerated efficient synthesis of aminobenzochromenes using Ag2Cr2O7 nanoparticles as a reusable heterogeneous catalyst

Ag₂Cr₂O₇ nanoparticles were found to be an exceedingly effective catalyst for the mild and green synthesis of aminobenzochromenes. The reaction was performed under ultrasonic irradiation as an innocuous tool and in water as a green solvent at room temperature. This method encompasses several sustainable and economic benefits.     

Acetone Dimethyl Hydrazone: Useful Synthon+ for the Synthesis of Pheromones with Keto and Spiro Ketal Functions

The use of α-lithiated dimethyl hydrazones as an efficient enolate equivalent for the alkylation of ketones has been reported^1,2,3. Due to the ragioselectivity exhibited by acetone dimethyl hydrazone (1) towards the formation of bis alkylated products, we have used the easily avaiLable (1) as a convenient synthon for achieving a short and simple synthesis of pheromones, 1,7-dioxaspiro (5,5) undecane4 (2) and Z-6-Heneicosen-11-one (2). The key step in both the syntheses is the regioselective bis alkylation of (1) using butyl lithium as a base, as shown in Scheme I.     

High contrast electromagnetically induced transparency in a nitrogen filled Rb vapour cell

We observe the electromagnetically induced transparency (EIT) spectra inside a nitrogen filled Rb vapour cell (Rb-N₂) in a five-level Λ-type system of D₂ transition of Rb atom. The high contrast EIT resonance in buffer gas filled Rb cell is obtained under our experimental conditions. The effect of velocity changing coherence preserving collisions to obtain the contrast resonance in buffer gas cell has been discussed. We measured the dependence of EIT width and height on pump intensity and find that the EIT width (FWHM) and peak height have a linear dependence on pump intensity. Our experimental results show that the presence of N2 buffer gas reduces the power broadening of the observed resonances.