High-Performance Thin-Layer Chromatographic Analysis of Bicalutamide in Bulk Drug and Liposomes

JPC – Journal of Planar Chromatography – Modern TLC - A sensitive, accurate, precise, and specific high-performance thinlayer chromatographic (HPTLC) method for analysis of bicalutamide...     

Stereodivergent Synthesis of 17‐α and 17‐β‐Aryl Steroids: Application and Biological Evaluation of D‐Ring Cortistatin Analogues

One stereocenter makes all the difference : The synthesis and biological evaluation of 17‐epi‐cortistatin A is reported from a common intermediate used to procure natural cortistatin A. The synthesis features a unique stereocontrolled Raney‐Ni reduction process that can be employed to reliably produce both α‐ and β‐configured D‐ring aryl steroids. Biological evaluations of these “cortalogs” are reported for the first time.

     

Asymmetric oxidation of sulfides catalyzed by (R)-6,6'-dibromo-BINOL derived titanium complex

Abstract

An efficient asymmetric oxidation of sulfides was achieved using (R)-6,6'-dibromo-BINOL as chiral ligand in combination with Ti(OⁱPr)₄ using 70% aqueous tertiary butyl hydroperoxide as oxidant. The resulting sulfoxides had high enantiopurities and good yields. A range of aryl alkyl and aryl benzyl sulfides were oxidized to the corresponding sulfoxides with 78–95% ee in 72–80% yields.     

Decoherence and surface hopping: when can averaging over initial conditions help capture the effects of wave packet separation?

Fewest-switches surface hopping (FSSH) is a popular nonadiabatic dynamics method which treats nuclei with classical mechanics and electrons with quantum mechanics. In order to simulate the motion of a wave packet as accurately as possible, standard FSSH requires a stochastic sampling of the trajectories over a distribution of initial conditions corresponding, e.g., to the Wigner distribution of the initial quantum wave packet. Although it is well-known that FSSH does not properly account for decoherence effects, there is some confusion in the literature about whether or not this averaging over a distribution of initial conditions can approximate some of the effects of decoherence. In this paper, we not only show that averaging over initial conditions does not generally account for decoherence, but also why it fails to do so. We also show how an apparent improvement in accuracy can be obtained for a fortuitous choice of model problems, even though this improvement is not possible, in general. For a basic set of one-dimensional and two-dimensional examples, we find significantly improved results using our recently introduced augmented FSSH algorithm.     

Simultaneous-trajectory surface hopping: a parameter-free algorithm for implementing decoherence in nonadiabatic dynamics

In this paper, we introduce a trajectory-based nonadiabatic dynamics algorithm which aims to correct the well-known overcoherence problem in Tully's popular fewest-switches surface hopping algorithm. Our simultaneous-trajectory surface hopping algorithm propagates a separate classical trajectory on each energetically accessible adiabatic surface. The divergence of these trajectories generates decoherence, which collapses the particle wavefunction onto a single adiabatic state. Decoherence is implemented without the need for any parameters, either empirical or adjustable. We apply our algorithm to several model problems and find a significant improvement over the traditional algorithm.     

Identification of New Non-BBB Permeable Tryptophan Hydroxylase Inhibitors for Treating Obesity and Fatty Liver Disease

Serotonin (5-hydroxytryptophan) is a hormone that regulates emotions in the central nervous system. However, serotonin in the peripheral system is associated with obesity and fatty liver disease. Because serotonin cannot cross the blood-brain barrier (BBB), we focused on identifying new tryptophan hydroxylase type I (TPH1) inhibitors that act only in peripheral tissues for treating obesity and fatty liver disease without affecting the central nervous system. Structural optimization inspired by para-chlorophenylalanine (pCPA) resulted in the identification of a series of oxyphenylalanine and heterocyclic phenylalanine derivatives as TPH1 inhibitors. Among these compounds, compound 18i with an IC₅₀ value of 37 nM was the most active in vitro. Additionally, compound 18i showed good liver microsomal stability and did not significantly inhibit CYP and Herg. Furthermore, this TPH1 inhibitor was able to actively interact with the peripheral system without penetrating the BBB. Compound 18i and its prodrug reduced body weight gain in mammals and decreased in vivo fat accumulation.     

Multiquantum vibrational excitation of NO scattered from Au(111): quantitative comparison of benchmark data to ab initio theories of nonadiabatic molecule-surface interactions

Surface phenomena: measurements of absolute probabilities are reported for the vibrational excitation of NO(v=0→1,2) molecules scattered from a Au(111) surface. These measurements were quantitatively compared to calculations based on ab?initio theoretical approaches to electronically nonadiabatic molecule-surface interactions. Good agreement was found between theory and experiment (see picture; T(s) =surface temperature, P=excitation probability, and E=incidence energy of translation).     

Total synthesis of (+/-)-chartelline C

The first total synthesis of (+/-)-chartelline C in a concise 10-step sequence is reported. Highlights of the completion of this decades-old puzzle include (1) chemo- and position-selective installation of the heteroaromatic halogens, (2) halogen-sparing monoreduction of an alkyne linker, (3) a simple strategy for placement of the sensitive beta-chloroenamide, (4) an unusually facile thermolysis of a vinyl carboxylic acid, and (5) a powerful ring contraction whose potential utility in heterocyclic chemistry merits further investigation.     

Coherent crosstalk in passive microring based Optical Networks-on-Chip

Optical Networks-on-Chip (ONoC) is emerging technology for future optical interconnects used in all optical networks. The electrical interconnects face lot of problems due to their inability to support higher data rates used in the System-on-Chip (SoC) technologies. Integrated optical interconnects based on SoC avoid this bottleneck with their support to higher data rates. In this paper for the first time we have studied and analyzed ONoC at physical level for the system performance based on crosstalk, BER, throughput, system frequency, and other related parameters. The investigation of ONoC performance is carried out for the multistage microring optical crossconnect on SoC for coherent WDM signals. The analysis can be used in the design of ultra-high speed photonic routers for reliable data communication and processing. The results show the dependency of a coherent crosstalk on the system frequency of SoC and also illustrate the reduction in throughput with increase in number of WDM signals due to higher probability of packet transmission. Minimum 2 dB signal to noise ratio can be obtained when crosstalk is ?25 dB with 60 wavelengths for probability of packet transmission is 0.5.