Synthesis of novel tryptamine and β-carboline derivatives via palladium-catalyzed reaction of bromotryptamine with organic boronic acids

New tryptamine 5, 7 and β-carboline derivatives 3 were preparated by palladium-catalyzed coupling reaction of 5-bromotryptamine 1 with aryl boronic acids. Dedicated to Professor András Lipták on his 70^th birthday.     

High-pressure dissociation of crystalline para-diiodobenzene: optical experiments and Car-Parrinello calculations

We have investigated the high-pressure properties of the molecular crystal para-diiodobenzene, by combining optical absorption, reflectance, and Raman experiments with Car-Parrinello simulations. The optical absorption edge exhibits a large red shift from 4 eV at ambient conditions to about 2 eV near 30 GPa. Reflectance measurements up to 80 GPa indicate a redistribution of oscillator strength toward the near-infrared. The calculations, which describe correctly the two known molecular crystal phases at ambient pressure, predict a nonmolecular metallic phase, stable at high pressure. This high-density phase is characterized by an extended three-dimensional network, in which chemically bound iodine atoms form layers connected by hydrocarbon bridges. Experimentally, Raman spectra of samples recovered after compression show vibrational modes of elemental solid iodine. This result points to a pressure-induced molecular dissociation process which leads to the formation of domains of iodine and disordered carbon.     

Benzodiazepine analogues. Part 21. 13C NMR analysis of benzoxathiepine derivatives

The influence of substituents and structure on the 13C NMR spectra of four series of benzoxathiepine derivatives has been investigated. Signal assignments in the 13C NMR spectra have been facilitated by the use of several predictive methods, permitting comparison of their relative efficacy.     

Xyloketal G,a Novel Metabolite from the Mangrove Fungus <Emphasis Type="Italic">Xylaria sp.</Emphasis> 2508

A novel metabolite 1, named xyloketal G, was isolated from cultures of marine derived mangrove fungus Xylaria sp. 2508. Its structure was elucidated by analysis of spectroscopic data.__________Published in Khimiya Prirodnykh Soedinenii, No. 1, pp. 22–23, January–February, 2005.     

Assessment of the Fe-Sn-Zn phase diagram at 450°C

The Fe-Sn-Zn system is of interest because Sn is one element added to the Zn galvanizing bath to overcome the drawbacks due to the presence of Si in semi-killed steels. This work has been undertaken with the aim to understand the tin effect on the microstructure and the layers growth in batch galvanized coatings on low alloyed steels. Various experimental techniques such as metallography, scanning electron microscopy (SEM) coupled with X-ray energy dispersive spectroscopy (EDX) are used in order to characterize the microstructure and the properties of such coatings elaborated in a zinc bath enriched with tin. Solidification phenomena and layers growth mechanisms during galvanization are explained by means of the ternary phase diagram Fe-Sn-Zn at 450°C. The Calphad method allows to obtain this phase diagram from the three optimized binary phase diagrams Fe-Sn, Fe-Zn and Sn-Zn and some experimental data inside the ternary Fe-Sn-Zn system.     

Chiral discrimination within disordered adlayers on metal surfaces

Using a novel non-linear optical technique enantiomeric excess within a translationally disordered overlayer on a metal surface has been monitored for the first time.     

Convenient Asymmetric Syntheses of anti-beta-Amino Alcohols

Condensation of allylborane reagents 9 and 12 with aldehydes gave anti-3-[(diphenylmethylene)amino]-1-alken-4-ols 10 and 13 with high relative and absolute stereocontrol. Subsequent deprotection gave the corresponding free anti-3-amino-1-alken-4-ols 11 and 14. Alternatively, reaction of imines 13a, 13f, and 13g with trifluoromethanesulfonic anhydride and acidic methanol gave, via rearrangement, double inversion, and hydrolysis, the isomeric anti-4-amino-1-alken-3-ols 22, 38a, and 38b in good yield. The stereochemistry of the rearrangement products has been established by a single crystal X-ray study of compound 37 and by chemical correlation.     

High-throughput protein crystallography and drug discovery

Single crystal X-ray diffraction is the technique of choice for studying the interactions of small organic molecules with proteins by determining their three-dimensional structures; however the requirement for highly purified protein and lack of process automation have traditionally limited its use in this field. Despite these shortcomings, the use of crystal structures of therapeutically relevant drug targets in pharmaceutical research has increased significantly over the last decade. The application of structure-based drug design has resulted in several marketed drugs and is now an established discipline in most pharmaceutical companies. Furthermore, the recently published full genome sequences of Homo sapiens and a number of micro-organisms have provided a plethora of new potential drug targets that could be utilised in structure-based drug design programs. In order to take maximum advantage of this explosion of information, techniques have been developed to automate and speed up the various procedures required to obtain protein crystals of suitable quality, to collect and process the raw X-ray diffraction data into usable structural information, and to use three-dimensional protein structure as a basis for drug discovery and lead optimisation.This tutorial review covers the various technologies involved in the process pipeline for high-throughput protein crystallography as it is currently being applied to drug discovery. It is aimed at synthetic and computational chemists, as well as structural biologists, in both academia and industry, who are interested in structure-based drug design.     

A re-statement of the Hohenberg–Kohn theorem and its extension to finite subspaces

Bearing in mind the insight into the Hohenberg–Kohn theorem for Coulomb systems provided recently by Kryachko (Int J Quantum Chem 103:818, 2005), we present a re-statement of this theorem through an elaboration on Lieb’s proof as well as an extension of this theorem to finite subspaces. Contribution to the Serafin Fraga Memorial Issue.     

Synthesis of monofluorinated 1-(naphthalen-1-yl)piperazines

A series of regioisomerically monofluorinated 1-(naphthalen-1-yl)piperazines is described.