A novel and diastereoselective construction of H-pyrazolo[3,2-a]isoquinoline fused spirooxindoles via [3+2] cycloaddition

A one-pot, highly efficient and diastereoselective construction of 1,2-dihyro-10′bH-spiro[indole-3,1′-pyrazole[3,2-a]isoquinoline]-2′-carboxylates via silver triflate-catalyzed [3+2] cycloaddition of N′-(2–alkynylbenzylidene)hydrazide with methyleneindolinones in good to excellent yield has been described. The transformation involves initially a condensation followed by 6-endo-intramolecular cyclization forming dipole which then undergoes [3+2]-cycloaddition with methyleneindolinones and finally, β-hydrogen elimination.     

Potential dependent thiocyanate adsorption on gold electrodes: a comparison study between SERS and SHINERS

Potential dependent adsorption of target molecules on electrode surface has long been analyzed by several analytical techniques at the electrochemical interfaces. Here, the adsorption of thiocyanate (SCN⁻) on gold electrodes [Au (111) and Au (poly)] is investigated by electrochemical shell isolated nanoparticle‐enhanced Raman spectroscopy (EC‐SHINERS) and surface‐enhanced Raman spectroscopy. Based on the experimental observation, C − N stretching mode of N‐bound SCN⁻ can be observed around 2080 cm⁻¹ throughout the whole potential range. The band corresponding to ν_C−N of S‐bound SCN⁻ appears as a shoulder at more negative potentials, and as a well‐defined band are more positive potentials. However, the overlapped bands provoke a negative shift in the frequency of S‐bound thiocyanate. Therefore, a change in the calculated Stark slope is observed. Interestingly, SHINERS has been employed to demonstrate the thiocyanate orientation and its effect on Raman spectra. Our results widen the opportunities of SHINERS to unravel the potential‐dependent adsorption behavior of target molecules on single‐crystal electrode surfaces. Copyright © 2016 John Wiley & Sons, Ltd.     

The First One‐Pot,Solvent‐Free,Microwave‐Accelerated,Three‐Component Synthesis of Spirothiazolidin‐4‐ones via Staudinger/Aza‐Wittig Coupling/Cyclization

An efficient and rapid, solvent‐free, microwave‐accelerated, one‐pot, three‐component protocol for the synthesis of spirothiazolidin‐4‐ones from organic azides is reported for the first time via Staudinger/aza‐Wittig coupling/cyclization. The solvent‐free approach overcomes the limitations associated with the prevailing solution‐phase methodologies in the case of amines. In particular, its novelty is that it eradicates the vital limitation, i.e., the accumulation of H₂O (by‐product), which is known to affect the yield and rate of the reaction, thus affording the spirothiazolidin‐4‐ones in short reaction times in excellent yields.