Asymmetric syntheses of (1R,1R,5R,7R) and (1S,1R,5R,7R)-1-hydroxy-exo-brevicomin and a formal synthesis of (+)-exo-brevicomin

Asymmetric syntheses of (1R,1^′R,5^′R,7^′R) and (1S,1^′R,5^′R,7^′R)-1-hydroxy-exo-brevicomins 1 and 2, volatiles of the male mountain pine beetle, and a formal synthesis of (+)-exo-brevicomin 3, a component of the attracting pheromone system of several bark beetles have been achieved. The key steps are Birch reduction of commercially available α-picoline, selective Wittig olefination, and Sharpless asymmetric dihydroxylation.     

A stereoselective synthesis of the hexahydroazepine core of (−)-balanol

A stereoselective synthesis of the hexahydroazepine core of (−)-balanol is described. The key step of the route includes the bromosulfonamidation of an olefin using the intramolecular sulfilimine group as the nucleophile and the Pummerer ene reaction.     

Synthesis,characterization, single crystal X-ray diffraction and DFT studies of ethyl 5-methyl-1-phenyl-1H-pyrazole-4-carboxylate

The present study describes the synthesis, spectroscopic, and single crystal X-ray structural analysis of ethyl 5-methyl-1-phenyl-1H-pyrazole-4-carboxylate. The pyrazole ester of formula [C₁₃H₁₄N₂O₂] was prepared from the three-component one-pot condensation reaction of ethyl acetoacetate, N,N-dimethyldimethoxymethanamine, and phenyl hydrazine. The product was crystallized by using ethanol as solvent. The structure of the compound was confirmed by elemental analysis, Fourier transforms infrared (IR), thermogravimetric analysis, UV-visible (UV-Vis), ¹H NMR, and single-crystal X-ray diffraction studies. The gas-phase molecular geometry and the electronic structure-property of the molecule were calculated at the density functional theory. The frontier molecular orbitals, theoretical UV-Vis, and IR stretching vibrations were also reported. The compound crystallizes in the monoclinic system with the space group P2₁/c and Z = 4. The unit cell parameters are a = 12.141(3) Å, b = 13.934(4) Å, c = 7.2777(18) Å, and β = 97.816(14)⁰. The structure is stabilized by an intermolecular interaction of type C-H···O and the structure also involves C-H···π interactions.     

Atomically Precise Defective Copper Nanocluster Catalysts for Highly Selective C−C Cross-Coupling Reactions

Point defects in nanoparticles have long been hypothesized to play an important role in governing the particle's electronic structure and physicochemical properties. However, single point defects in material systems usually exist with other heterogeneities, obscuring the chemical role of the effects. Herein, we report the synthesis of novel atomically precise, copper hydride nanoclusters (NCs), [Cu₂₈H₁₀(C₇H₇S)₁₈(TPP)₃] ( Cu₂₈ ; TPP: triphenylphosphine; C₇H₇S: o-thiocresol) with a defined defect in the gram scale via a one-pot reduction method. The Cu₂₈ acts as a highly selective catalyst for C−C cross-couplings. The work highlights the potential of defective NCs as model systems for investigating individual defects, correlating defects with physiochemical properties, and rationally designing new nanoparticle catalysts.     

Self-defocusing/focusing of a relativistic laser pulse in a multiple-ionizing gas

A fast rising flattop high power laser pulse, with Gaussian intensity distribution along its wavefront, causes single and double ionizations of the gas through which it propagates. The foot of the pulse causes single ionization of the gas and creates a sharp radial density profile resulting in strong defocusing of the front part of the pulse. After a little while, single state ionization saturates, creating a flat density profile in the axial region and weakening the divergence of the pulse. As the intensity of the pulse rises further, second state ionization occurs, causing strong defocusing of the beam. Later in time when the second state ionization saturates, the relativistic mass nonlinearity together with the electron cavitation tends to focus the pulse.     

Design,synthesis and spectroscopic and crystallographic characterisation of novel functionalized pyrazole derivatives: biological evaluation for their cytotoxic,angiogenic and antioxidant activities

Research on Chemical Intermediates - The current study presents the synthesis of functionalized pyrazoles (18–29) through 3?+?2 annulation reaction of ethyl...     

Structural,spectral, and theoretical investigations of 5-methyl-1-phenyl-1H-pyrazole-4-carboxylic acid

Research on Chemical Intermediates - The present research work has focused on combined experimental and theoretical studies of one of the biologically important pyrazole-4-carboxylic acid...     

Brookhart's Acid-Catalyzed Switchable Regioselective N-Alkylation of Arylamines/Heterocyclic Amines with Cyclopropylcarbinols by Temperature Regulation

An unprecedented, Brookhart's acid-catalyzed temperature-switchable regioselective divergent approach for N-alkylation of arylamines and heterocyclic amines by utilising cyclopropylcarbinols is presented herein. The reaction offers N-alkylated cyclopropyl derivatives and homoallyl amines by employing 2.5 mol% catalyst loading at different temperatures in excellent regioselectivity and yields. This method has shown to be relevant with a wide range of cyclopropylcarbinols, including aliphatic ones. Several control experiments and spectroscopic studies have been performed to gain insight into the reaction mechanism. Further, the synthetic utility of the protocol has also been described.