Quantification of 1‐(propan‐2‐ylamino)‐4‐propoxy‐9H‐thioxanthen‐9‐one (TX5), a newly synthetized P‐glycoprotein inducer/activator,in biological samples: method development and validation

A simple, rapid and economical method was developed and validated for the analysis and quantification of 1‐(propan‐2‐ylamino)‐4‐propoxy‐9H ‐thioxanthen‐9‐one (TX5), a P‐glycoprotein inducer/activator, in biological samples, using reverse‐phase high‐performance liquid chromatography (HPLC). A C₁₈ column and a mobile phase composed of methanol–water (90/10, v /v) with 1% (v/v) triethylamine, at a flow rate of 1 mL/min, were used for chromatographic separation. TX5 standards (0.5–150 μm ) were prepared in human serum. Methanol was used for TX5 extraction and serum protein precipitation. After filtration, samples were injected into the HPLC apparatus and TX5 was quantified by a conventional UV detector at 255 nm. The TX5 retention time was 13 min in this isocratic system. The method was validated according to ICH guidelines for specificity/selectivity, linearity, accuracy, precision, limits of detection and quantification (LOD and LOQ) and recovery. The method was proved to be selective, as there were no interferences of endogenous compounds with the same retention time of TX5. Also, the developed method was linear (r ² ≥ 0.99) for TX5 concentrations between 0.5 and 150 μm and the LOD and LOQ were 0.08 and 0.23 μm , respectively. The results indicated that the reported method could meet the requirements for TX5 analysis in the trace amounts expected to be present in biological samples.     

STEREOSELECTIVE REACTIONS OF CHIRAL AMINES WITH RACEMIC CHLOROPHOSPHINES

Racemic chlorophosphines react stereoselectively with chiral l-phenylethylamines or amino acid esters to give diastereomerically enriched aminophosphines 3, which were isolated as diastereomerically pure crystalline borane complexes. Oxidation, thionation, the reaction with methyl iodide provide optically active derivatives of aminophosphines. (R,S)- and (S,S)-stereomers of phosphinic acid amides were separated by crystallization and a flash-chromatography. The stereochemical properties of phosphorus acid amides were investigated. The mechanism of asymmetric induction at the trivalent phosphorus atom was rationalized.     

Diasteroselective Addition of Monoand Bis-Silylphosphines to Chiral Aldehydes

Abstract

The addition of silylphosphines to chiral aldehydes proceeds with high diastereoselectivity to give optically pure tertiary α -trimethylsiloxyalkylphosphines. The diastereomeric excesses of the addition products were achieved to 90–100%. The reaction of bis(trimethylsilyl)phenylphosphine with the acetonide of (R)-glyceraldehyde provides diastereomerically enriched tertiary bis(glyceryl)phosphines.     

SYNTHESIS AND CONFORMATIONAL STUDIES OF A NUMBER OF SATURATED BICYCLIC SIX-MEMBERED RING PHOSPHITES

Abstract

An ¹H NMR study of the conformation of the dioxaphosphorinane ring of a number of diastereoisomeric bicyclic saturated six-membered ring phosphites (3ab-10ab) has been performed. The dioxaphosphorinane ring of these phosphites is transannelated with a tetrahydrofuran, cyclopen-tane, tetrahydropyran or cyclohexane ring. The substituent on the phosphorus atom is a methoxy or phenoxy group. It is shown that the cis isomers 3a-10a prefer a chair conformation of the dioxaphosphorinane ring, independent of the substituent on the phosphorus atom and of the nature of the transannelated ring. In contrast, for the trans isomers 3b-10b a twist rather than a chair conformation of the dioxaphosphorinane ring is preferred. The fraction of the twist conformer in the trans isomers is mainly determined by the substituent on phosphorus. The size and composition of the transannelated ring are relatively unimportant in this respect. For both cis and trans isomers the preferred geometry is solvent-independent. The measured ^3JPOCH couplings of the cis isomers 3a-10a are used to formulate an expression for the dependence of such couplings upon dihedral angles in bicyclic phosphites.     

Oxidative Stabilization of Poly(norbornene) Polymers Prepared by Ring Opening Metathesis Polymerization

Polymers prepared by ring opening methathesis polymerization contain double bonds along the backbone and are susceptible to oxidation during high temperature processing or device operation. To overcome this, we report a simple method to improve the oxidative stability of ROMP based polymers by inclusion of a small percentage of monomer functionalized with a radical scavenger in the feedstock. The oxidation induction temperature was improved from 111°C up to 262°C when 8 mol% of the functionalized comonomer was included in the feedstock. Modest improvements in the thermal decomposition temperature were also observed.     

Ionic Copolymerizations

It is shown that for the reported instances of “random” copolymerization in cationic systems, N values related to relative reactivity may be derived for monomers. The N values approximate reasonably well the values of the function, exp (-e) - 1.23, where e is the polarity e of the Q-e scheme for free-radical copolymerizations.

In a recent paper [1] it was shown that for the reported instances [2-4] of “random” copolymerization (r₁,r₂ = 1) in cationic systems, N values, related to relative reactivity, might be derived for monomers, employing styrene as a base monomer (N = 1). Thus d[M₁]/d[M₂] =N₁[M₁]/N₂[M₂] (1)

where d[M₁]/d[M₂] is the instantaneous copolymer composition, [M₁]/[M₂] is the ratio of unreacted monomers, and N₁ and N₂ are parameters related to general monomer reactivity of monomers 1 and 2, respectively, in cationic copolymerization.     

Synthesis and Reaction of Some Indenopyridine and Thieno[2,3-b]Indeno[2,1-e]Pyridine Derivatives

Synthesis of indenopyridine-2-thione derivatives 6a-e via reaction of compound 1 with thioamides 2a-e in good yields. Several thieno[2,3-b]indeno[2,1-e]pyridine 9a-e have been synthesized. Some of them was used as a key intermediate in synthesis of 10-12. On the other hand, compound 1 reacted with various reagents to yield 16, 19, 21-24.     

Synthesis and Properties of Surfactants derived from N‐Acetyl‐D‐Glucosamine

The synthesis of 2‐acetamido‐2‐deoxy‐6‐O‐octanoyl‐D‐glucono‐1,5‐lactone 9 and 2‐acetamido‐2‐deoxy‐6‐O‐octanoyl‐α‐D‐glucopyranose 7 from 2‐acetamido‐2‐deoxy‐α‐D‐glucopyranose is reported. For both targets, the key intermediate was allyl 2‐acetamido‐3,4‐di‐O‐benzyl‐2‐deoxy‐6‐O‐octanoyl‐α‐D‐glucopyranoside 5. Surface tension measurements (critical micellar concentration of 22.3 mM and 5 mM for 9 and 7, respectively) showed up the surface activity of both compounds, while enzyme inhibition assays indicated that 9 could inhibit bovine β‐N‐acetylglucosaminidase (K_i=6.5 µM) but not Serratia marcescens chitobiase nor hen egg‐white lysozyme. Moreover, 7 was shown to induce chitinase production of S. marcescens and to be readily metabolized by these bacteria.