Mobility and Solvation Structure of Hydroxyl Radical in a Water Nanodroplet: A Born-Oppenheimer Molecular Dynamics Study

Hydroxyl radical (OH*) plays a crucial role in atmospheric chemistry and biological processes. In this study, density func-tional theory (DFT)-based Born-Oppenheimer molecular dynamics (BOMD) simulations are performed under ambient condi-tions...

Global Diastereoconvergence in the Ireland–Claisen Rearrangement of Isomeric Enolates: Synthesis of Tetrasubstituted -Amino Acids

<div><div><div><p>A dual experimental/theoretical investigation of the Ireland–Claisen rearrangement of tetrasubstituted a-phthalimido ester enolates to afford a-tetrasubstituted, b-trisubstituted a-amino acids (generally >20:1 dr) is described. For trans allylic olefins, the Z and E-enol ethers proceed through chair and boat transition states, respectively. For cis allylic olefins, the trend is reversed. As a result, the diastereochemical outcome of the reaction is preserved regardless of the geometry of the enolate or the accompanying allylic olefin. We term this unique convergence of all possible olefin isomers as global diastereoconvergence. This reaction manifold circumvents limitations in present-day technologies for the stereoselective enolization of a,a-disubstituted allyl esters. Density func- tional theory paired with state-of-the-art local coupled-cluster theory (DLPNO-CCSD(T)) was employed for the accurate determina- tion of quantum mechanical energies.</p></div></div></div>

Global Diastereoconvergence in the Ireland–Claisen Rearrangement of Isomeric Enolates: Synthesis of Tetrasubstituted -Amino Acids

<div><div><div><p>A dual experimental/theoretical investigation of the Ireland–Claisen rearrangement of tetrasubstituted a-phthalimido ester enolates to afford a-tetrasubstituted, b-trisubstituted a-amino acids (generally >20:1 dr) is described. For trans allylic olefins, the Z and E-enol ethers proceed through chair and boat transition states, respectively. For cis allylic olefins, the trend is reversed. As a result, the diastereochemical outcome of the reaction is preserved regardless of the geometry of the enolate or the accompanying allylic olefin. We term this unique convergence of all possible olefin isomers as global diastereoconvergence. This reaction manifold circumvents limitations in present-day technologies for the stereoselective enolization of a,a-disubstituted allyl esters. Density func- tional theory paired with state-of-the-art local coupled-cluster theory (DLPNO-CCSD(T)) was employed for the accurate determina- tion of quantum mechanical energies.</p></div></div></div>

Structural and electronic properties of boron- bismuth compound under pressure

<p>In the present work, we report first principles calculations of the pressure effect on the structural and electronic properties of Boron- Bismuth (BBi) compound in its zincblende phase. The pseudopotential plane wave (PPW) method in the framework of the density func-tional theory (DFT) within the local density approximation for the exchange-correlation functional, and the Hartwigzen-Goedecker-Hutter (HGH) scheme for the pseudopotential were used in the calculation. The unit cell volume, the molecular and crystal densities, the equation of state and also the linear and quadratic pressure coefficients of the energy band-gaps are investigated.</p>