Palladium-catalyzed chemoselective direct α-arylation of carbonyl compounds with chloroaryl triflates at the C–Cl site

This study described palladium-catalyzed chemoselective direct α-arylation of carbonyl compounds with chloroaryl triflates in the Ar–Cl bond. The Pd/SelectPhos system showed excellent chemoselectivity toward the Ar–Cl bond in the presence of the Ar–OTf bond with a broad substrate scope and excellent product yields. The electronic and steric hindrance offered by the –PR₂ group of the ligand with the C2-alkyl group was found to be the key factor affecting the reactivity and chemoselectivity of the α-arylation reaction. The chemodivergent approach was also successfully employed in the synthesis of flurbiprofen and its derivatives (e.g., –OMe and –F).

Palladium-catalyzed chemoselective direct α-arylation of carbonyl compounds with chloroaryl triflates in the Ar–Cl bond is reported. The effects of –PR₂ and C2-alkyl groups of the ligands are investigated using experimental and computational methods.     

Short and simple synthesis of chelating bis-ethers and bis-amines in the bicyclo[3.3.1]nonane series

A remarkably simple process for the synthesis of a series of rigid bicyclic diethers and diamines is described.     

Soft magnetic properties and giant magneto-impedance effect of Fe73.5−xCrxSi13.5B9Nb3Au1 (x=1–5) alloys

In this paper, the effect of microstructural and surface morphological developments on the soft magnetic properties and giant magneto-impedance (GMI) effect of Fe_73.5−xCr_xSi_13.5B₉Nb₃Au₁ (x=1, 2, 3, 4, 5) alloys was investigated. It was found that the Cr addition causes slight decrease in the mean grain size of α-Fe(Si) grains. AFM results indicated a large variation of surface morphology of density and size of protrusions along the ribbon plane due to structural changes caused by thermal treatments with increasing Cr content. Ultrasoft magnetic properties such as the increase of magnetic permeability and the decrease of coercivity were observed in the samples annealed at 540 °C for 30 min. Accordingly, the GMI effect was also observed in the annealed samples.     

Modelling coupled water and heat transport in a soil–mulch–plant–atmosphere continuum (SMPAC) system

This paper presents a physically based model coupling water and heat transport in a soil–mulch–plant–atmosphere continuum (SMPAC) system, in which a transparent polyethylene mulch is applied to a winter wheat crop. The purpose of the study is to simulate profiles of soil water content and temperature for different stages of wheat growth. The mass and energy balance equations are constructed to determine upper boundary conditions of governing equations. Energy parameters are empirically formulated and calibrated from three-month field observed data. Resistance parameters in the SMPAC system are calculated. The mass and energy equations are solved by an iterative Newton–Raphson technique and a finite difference method is used to solve the governing equations. Water-consuming experiments are performed within the growing period of wheat. The results show that the model is quite satisfactory, particularly for high soil water content, in simulating the water and temperature profiles during the growth of the winter wheat.     

An alternative proof of some percolation threshold (p c ) using the idea of self-organized criticality

Summary By means of a well-developed method in self-organized criticality, we can obtain the lower bound for the percolation threshold (p _c) of the corresponding site percolation problem. In some special cases, we have proved that such lower bounds are indeed the percolation thresholds. We can reproduce some well-known percolation thresholds of various lattices including the Cayley trees and Kock curves in this framework.     

A Practical Formal Synthesis of a Physiologically Active Analogue of Platelet Activating Factor

A synthesis of phosphocholine 9 was accomplished in 36% yield from isopropylidene glycerol in contrast to 2% yield as reported previously. Since 9 has been converted to platelet activating factor-analogue 2, this report constitutes a more practical synthesis of 2.     

Ab initio calculations and Franck-Condon simulation of the absorption spectra of GeCl2 including anharmonicity.

Geometrical parameters, vibrational frequencies and relative electronic energies of the X1A1, ?3B1 and A1B1 states of GeCl2 have been calculated at the CCSD(T) and/or CASSCF/MRCI level with basis sets of up to aug-cc-pV5Z quality. Core electron correlation and relativistic contributions were also investigated. RCCSD(T)/ aug-cc-pVQZ potential energy functions (PEFs) of the X1A1 and ?3B, states, and a CASSCF/MRCl/aug-cc-pVQZ PEF of the A1B1 state of GeCl2 are reported. Anharmonic vibrational wavefunctions of these electronic states of GeCl2, obtained variationally using the computed PEFs, are employed to calculate the Franck-Condon factors (FCFs) of the ?-X and A-X transitions of GeCl2. Simulated absorption spectra of these transitions based on the computed FCFs are compared with the corresponding experimental laser-induced fluorescence (LIF) spectra of Karolczak et al. [J. Chem. Phys. 1993, 98, 60-70]. Excellent agreement is obtained between the simulated absorption spectrum and observed LIF spectrum of the ?-X transition of GeCl2, which confirms the molecular carrier, the electronic states involved and the vibrational assignments of the LIF spectrum. However, comparison between the simulated absorption spectrum and experimental LIF spectrum of the A-X transition of GeCl2 leads to a revision of vibrational assignments of the LIF spectrum and suggests that the X1A1 state of GeCl2 was prepared in the experimental work, with a non-Boltzmann vibrational population distribution. The X(0,0,1) level is populated over 4000 times more than expected from a Boltzmann distribution at 60 K, which is appropriate for the relative population of the other low-lying vibrational levels, such as the X(1,0,0) and X(0,1,0) levels.