Rajeev R. Jha

Palladium-catalyzed regioselective [3 + 2] annulation of internal alkynes and iodo-pyranoquinolines with concomitant ring opening.

A regioselective tandem synthesis of highly functionalized pyrrolo[1,2-a]quinolines has been developed through a novel strategy by palladium-catalyzed [3 + 2] annulation of iodo-pyranoquinolines and internal alkynes with subsequent ring opening. Pyranoquinoline with n-alkyl substitution at the 3-position leads to the formation of pyrrolo-acridones via [3 + 2] annulations/ring opening and successive intramolecular cross-aldol condensation.

Pd(II) complexes with amide-based macrocycles: syntheses, properties and applications in cross-coupling reactions

This work shows Pd(II) complexes in a set of 13-membered amide-based macrocyclic ligands varied by the placement of e−-donating and e−-withdrawing substituents on the ligand framework. Ligands constitute a N4 square-planar cavity and optimally house the Pd(II) ion. The solution-state structure via NMR and absorption spectra substantiates the solid-state structure obtained by crystallography. The electrochemical studies display the impact of electronic substituents on ligands that significantly influence the redox properties and also shift the locus of oxidation. These complexes were used in the Suzuki and Heck cross-coupling reactions. The moderate cross-coupling reaction results are due to limited redox accessibility that can be improved either by using substrates with a better leaving group or by placing electron-withdrawing substituents on the macrocyclic ligands.

Direct electron heating experiment on the Aditya tokamak using fast waves in the ion cyclotron resonance frequency range

Second harmonic heating experiments using fast waves are carried out on the Aditya tokamak in the ion cyclotron resonance frequency (ICRF) range with the help of a 200?kW, 20?40?MHz RF heating system, which is developed indigenously. Significant direct electron heating is observed in a hydrogen plasma. The rise in electron temperature is prompt with the application of RF power and the increment in electron temperature increases linearly with RF power. A corresponding increase in plasma beta and hence an increase in stored diamagnetic energy are also observed in the presence of RF power. The low-Z impurity radiation and electron density do not increase significantly with RF power. The direct electron heating by fast wave in Aditya is also predicted by the ion cyclotron resonance heating code TORIC.

Direct Electron Heating Observed by Fast Waves in ICRF Range on a Low-Density Low Temperature Tokamak ADITYA

Fast wave electron heating experiments are carried out on Aditya tokamak [R = 0.75 m, a = 0.25m,Bt = 0.75T,ne∼1–3E13/cc,Te∼250eV] with the help of indigenously developed 200 kW, 20–40 MHz RF heating system. Significant direct electron heating is observed by fast waves in hydrogen plasma with prompt rise in electron temperature with application of RF power and it increases linearly with RF power. A corresponding increase in plasma beta and hence increase in stored diamagnetic energy is also observed in presence of RF. We observe an improvement of energy confinement time from 2–4msec during ohmic heating phase to 3‐6msec in RF heating phase. This improvement is within the ohmic confinement regime for the present experiments. The impurity radiation and electron density do not escalate significantly with RF power. The direct electron heating by fast wave in Aditya is also predicted by ion cyclotron resonance heating code TORIC.