Simple and efficient cleavage reaction of the boc group in heterocyclic compounds

Dedicated to the memory of Pr. Ladjama Daif A series of chiral cyclosulfamides have been synthesized by alkaline cyclisation starting from N‐benzoylamino acids (Ala, Val, Leu, Phe) derivatives and chlorosulfonyl isocyanate. A simplified and regioselective deprotection of the cyclic compounds (cyclosulfamides) containing the tert‐butyloxycarbonyl group (Boc) has been achieved in good yield by fusion under reduced pressure.     

A discontinuous Galerkin method/HLLC solver for the Euler equations

This paper proposes a fully three‐dimensional non‐linear Euler methodology for solving aerodynamic and acoustic problems in the presence of strong shocks and rarefactions. It uses a discontinuous Galerkin method (DGM) within the element, and a Riemann solver (HLLC) at the boundaries to propagate rarefactions while preserving the entropy condition and capturing shocks with no spurious oscillations. This approach is thought to marry the best aspects of finite element and finite volume methods, achieving conservation while not requiring the solution of a large matrix. Examples in which shock and rarefaction waves are well captured are presented and the propagation of acoustic pulses is well demonstrated. Copyright © 2003 John Wiley & Sons, Ltd.     

Validated HPLC method for simultaneous quantification of mutant IDH1/2 inhibitors (enasidenib,ivosidenib and vorasidenib) in mouse plasma: Application to a pharmacokinetic study

Isocitrate dehydrogenase (IDH) inhibitors comprise a novel class of anticancer drugs, which are approved to treat acute myeloid leukemia patients having mutations on IDH1/2. We report the development and validation of a high‐performance liquid chromatography (HPLC) method for the simultaneous quantitation of IDH inhibitors, namely enasidenib (EDB), ivosidenib (IDB) and vorasidenib (VDB), in mouse plasma as per the US Food and Drug Administration regulatory guidelines. The method involves extraction of EDB, IDB and VDB along with internal standard (IS; phenacetin) from mouse plasma (100 μl) using a simple protein precipitation process. The chromatographic analysis was performed on an HPLC system using a gradient mobile phase (comprising 10 mm ammonium acetate and acetonitrile in a flow‐gradient) and an X‐Terra Phenyl column. The UV detection wave length was set at λ_max 265 nm. EDB, IDB, VDB and the IS eluted at 7.36, 8.60, 9.50 and 5.12 min, respectively, with a total run time of 10 min. The calibration curve was linear over a concentration range of 0.20–12.5 μg/ml for EDB and 0.50–12.5 μg/ml for IDB and VDB (r² = ≥0.998 for all of the analytes). Validation results met the acceptance criteria. The validated HPLC method was successfully applied to a pharmacokinetic study in mice.     

Efficient Method for The Synthesis of α-Amidophosphonates via the Michaelis-Arbuzov Reaction

Abstract

A new series of modified α-amidophosphonates (or β-ketophosphonate) was synthesized by an efficient method, starting from aminoesters and chloroacetyl chloride. We have established that chloroacetyl chloride is a suitable reagent allowing the introduction a halogen moiety for the Arbuzov reaction. The α-amidophosphonates were prepared in two steps (acetylation, phosphorylation).

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Structural Basis for Carbapenemase Activity of the OXA-23 β-Lactamase from Acinetobacter baumannii

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Synthesis and Biological Activity of New Chiral N‐Acylsulfonamide Bis‐oxazolidin‐2‐ones

A new series of chiral 5‐substituted bis‐oxazolidinones containing an acylsulfonamide moiety has been synthesized starting from chlorosulfonyl isocyanate, (l )‐ethyl lactate, and oxazolidin‐2‐ones. All the reactions were conducted at ambient temperature, and the N‐acylsulfonamide bis‐oxazolidin‐2‐ones were obtained with high yields within 2 h. Some of the newly synthesized compounds were evaluated in vitro against the virulent strain RH of Toxoplasma gondii and the human lymphocytes, and showed promising results.     

A Very Short and Efficient Total Synthesis of Otanthus Maritima Amide.

A new total synthesis of Otanthus Maritima amide 1 was achieved from 6-trimetylsily N-tert-butyl sorbaldimine 6 in 76% global yield. The natural product 1 was obtained in three steps by condensation of 6 on thiophenal in the presence of catalytic amount of CsF (10%) in DMSO followed by oxidation and amidification of the corresponding intermediate.     

Improved Synthesis,Structure, and Solution Characterization of the Cyclic 48-Tungsto-8-Arsenate(V), [H4As8W48O184]36−

We report on an improved synthesis and structural characterization of the cyclic 48-tungsto–8-arsenate(V) [H₄As₈W₄₈O₁₈₄]^36? (1). The mixed lithium–potassium salt of this polyanion, K_26.5Li_9.5[H₄As₈W₄₈O₁₈₄]·90H₂O (KLi-1), has been studied in the solid state by IR, single-crystal X-ray diffraction, and elemental analysis, and in solution by ¹⁸³W NMR spectroscopy.     

Stability analysis of jointed rock slope

The stability analysis of a jointed rock slope with two sets of unfilled joints, under its own weight, is carried out directly by considering failure surfaces along some particular joints and also going through the intact rock. Simple failure mechanisms using uniform rigid rock-block motions are incorporated in the yield design kinematic approach. They yield an improvement of known results as long as the characteristics strength of the joints are weak enough.     

Fast characterization of functionalized silica materials by silicon-29 surface-enhanced NMR spectroscopy using dynamic nuclear polarization

We demonstrate fast characterization of the distribution of surface bonding modes and interactions in a series of functionalized materials via surface-enhanced nuclear magnetic resonance spectroscopy using dynamic nuclear polarization (DNP). Surface-enhanced silicon-29 DNP NMR spectra were obtained by using incipient wetness impregnation of the sample with a solution containing a polarizing radical (TOTAPOL). We identify and compare the bonding topology of functional groups in materials obtained via a sol-gel process and in materials prepared by post-grafting reactions. Furthermore, the remarkable gain in time provided by surface-enhanced silicon-29 DNP NMR spectroscopy (typically on the order of a factor 400) allows the facile acquisition of two-dimensional correlation spectra.