Spectroscopic investigation of light strange S=-1 Λ and Σ and S=-2 Ξ baryons

The present study is dedicated to light-strange Δ with strangeness S=-1 and isospin I=0,E with S=-1 and I=1,and Ξ baryon with S=-2 and I=1/2. In this study,the hypercentral constituent quark model with linear confining potential has been employed along with a first order correction term to obtain the resonance masses up to approximately 4 GeV.The calculated states include 1 S-5 S,1 P-4 P,1 D-3 D,1 F-2 F,and 1 G(in a few cases) along with all possible spin-parity assignments.Regge trajectories have been explored for the linearity of the calculated masseJ for(n,M2) and(J,M2).Magnetic moments have been intensively Ltudied for ground Utate spin 1/2 and 3/2, in addition to the configuration mixing of the first negative parity state for Ξ.Lastly,the transition magnetic moments and radiative decay widths have been presented.     

Isatin N-protected ketimines with nitromethane catalyzed by chiral binol linked monomeric macrocyclic Cu(II)–salen complex

Chiral Cu-1B generated in situ was used as an efficient catalyst for the synthesis of β-nitroamines in high yield (88%) with excellent enantioselectivity (ee up to 99%) at RT in absence of co-catalyst via asymmetric aza-Henry reaction of various isatin derived N-Boc ketimines with nitromethane. This catalytic system did not work well with other nitroalkanes under the above optimized reaction conditions. To examine this catalytic behaviour, quantum chemical DFT calculations were performed with the nucleophiles (CH₂NO₂^? and CH₃CHNO₂^?) for the conversion of 1a to 2a using macrocyclic Cu-1B complex. The DFT calculated results have shown that the reaction with CH₂NO₂^? is more favourable than the corresponding CH₃CHNO₂^?. The calculated activation barriers suggest that the reaction with CH₂NO₂^? is ～8.0?kcal/mol energetically favoured than CH₃CHNO₂^?. This catalytic protocol was further used to obtain chiral β-diamines (a building block for pharmaceuticals) at gram scale. In order to elucidate the reaction mechanism of asymmetric aza Henry reaction kinetic experiments were performed with different concentrations of the catalyst Cu-1B, nitromethane and 1g as the representative substrate. The reaction of isatin N-Boc ketimine was first order with respect to the concentration of the catalyst and the nitromethane but did not depend on the initial concentration of the substrate. A possible mechanism for the aza Henry reaction was proposed.