First enantiospecific synthesis of (+)-β-herbertenol

The first enantiospecific synthesis of (+)-β-herbertenol, from naturally occurring R-(+)-citronellal, employing Taber's diazo decomposition protocol as the key step, is described.     

Synthesis of carbon nanotubes by ECR plasma-assisted chemical vapor deposition

Carbon nanotubes have been grown using an electron cyclotron resonance (ECR) plasma source at a substrate temperature of 500 °C. Methane has been used as the source gas. A network of carbon nanotubes has been observed in scanning electron microscopy. Transmission electron microscopy revealed that the structure consists of straight, Y-junction and ring-like nanotubes. Further, electron diffraction of the nanotubes confirms a graphite crystal structure. PACS 81.16.He; 68.37.Lp; 68.37.Hk; 85.35.Kt; 75.75.+a     

Effect of random density irregularities on nonlinear evolution of Langmuir waves in interplanetary medium

The evolution of nonlinear Langmuir waves in the interplanetary medium is investigated by appropriately accounting for the random density irregularities of the medium. A pair of modified Zakharov equations, which describe these waves, is solved numerically as an initial value problem for large scale (≫ 10² km) initial pertubations. For an ion acoustic-Langmuir solitary wave, the random irregularities damp the Langmuir wave by way of scattering and let the ion density perturbation radiate away in a few days. However an initial solitary or shock-like Langmuir wave excites the ion density perturbations within a fraction of a second, and then itself gets damped. These effects will strongly decelerate the collapse of large scale Langmuir waves. The possibility of detecting these processes, by means of interplanetary scintillation, is discussed. The authors felicitate Prof. D S Kothari on his eightieth birthday and dedicate this paper to him on this occasion.     

Time-resolved spectra of coumarin 30-rhodamine 6G dye mixture

The effect of acceptor concentration on the energy transfer from Coumarin 30 (donor) to Rhodamine 6G (acceptor) has been studied. The nature of energy transfer reaction has been studied through lifetime measurements by recording the time-resolved fluorescence decay curves. The energy transfer parameters calculated were used to confirm the occurrence of energy transfer on the basis of the emission-reabsorption effect.     

Thiol derivatives of arylnaphthylmethane as novel anti-osteoporotic agents

(Mercaptophenyl)naphthylmethane derivatives were synthesized as novel estrogen receptor binding ligands. [4-(Methylsulfonyl)phenyl](naphth-1-yl)ketone shows a very promising activity towards osteoporosis. Correspondence: Sangita, Medicinal and Process Chemistry Division, Central Drug Research Institute, Lucknow 226001, India.     

Phosphosulfonic acid‐catalyzed green synthesis and bioassay of α‐aryl‐α′‐1,3,4‐thiadiazolyl aminophosphonates

A series of new α‐aminophosphonates containing 1,3,4‐thiadiazole moiety (4a–l) were synthesized via a simple, efficient, and one‐pot three‐component Kabachnik–Fields reaction of 2‐amino‐5‐ethyl‐1,3,4‐thiadiazole with various aryl/heteroaryl aldehydes and diethylphosphite under solvent‐free microwave irradiation conditions using phosphosulfonic acid, as a reusable and heterogeneous solid acid catalyst. All the title compounds were screened for radical scavenging activity by DPPH and H₂O₂ methods, and antimicrobial activity against bacteria (Gram‐positive and Gram‐negative) and fungi using the disc diffusion technique. They exhibited potent in vitro antioxidant and moderate antimicrobial activity.     

Reduction of chromano–piperidine-fused isoxazolidines: Tandem intramolecular rearrangements leading to 2-(methylamino)-4-oxo-N-phenyl-N-propyl-4H-chromene-3-carboxamide

Reductive ring opening of isoxazolidine moiety of chromano–piperidine-fused isoxazolidines (3a–c) with HCOONH₄ and 10% Pd/C in a mixture of solvents (THF/MeOH) at ambient temperature, affords novel 2-(methylamino)-4-oxo-N-phenyl-N-propyl-4H-chromene-3-carboxamide (4), which is apparently derived from reductive NO bond cleavage followed by tandem intramolecular rearrangements. Plausible mechanistic rationale for the formation of compound 4 is proffered.     

Sulfated choline ionic liquid-catalyzed acetamide synthesis by grindstone method

Sulfated choline ionic liquid (SCIL) has been found to be an efficient solid acid IL catalyst for the protection of amine groups with acetic anhydride under solvent-free grindstone conditions. The attractive features of this new catalytic methodology include its sustainability, facile work-up procedure, economic viability, and biodegradability. The SCIL catalyst was characterized using infrared spectroscopy, wide-angle X-ray scattering analysis, and scanning electron microscopy with energy dispersive X-ray spectroscopy. The catalyst could be reused six times without significant loss in activity. Furthermore, no chromatographic separations were needed to obtain the desired products.