Mechanisms for the cleavage of carbon-tin bonds : VI. A kinetic and stereochemical study of the halodemetallation of cyclopropyltrialkyltins: the solvent effect

The bimolecular halodemetallation of substituted cyclopropyltrialkyltins is stereospecific, and proceeds with retention of the configuration at carbon in methanol, acetic acid and chlorobenzene. The kinetic study confirms the hypothesis which was based on results for the R′SnR₃ series, and shows the participation of the ring orbitals in the rate determining step of the reaction.     

Synthesis,structural characterization and in vitro antitumour properties of triorganoantimony(V) disalicylates: Crystal and molecular structures of [5-Y-2-(ho)-C6H3COO]2SbMe3 (YH,Me, MeO)

Triorganoantimony(V) salicylates, [5-Y-2-(HO)-C₆H₃COO]₂SbR₃ (R=Me, Ph; Y=H, Me, MeO), were obtained by reacting R₃SbCl₂ with the appropriate sodium salt. The compounds have been characterized by IR, MS, ¹H and ¹³C NMR spectroscopy. The molecular structure of the three substituted trimethylantimony(V) disalicylates has been determined by X-ray diffraction. The salicylate ligands are mono-coordinated to antimony through an oxygen atom of each carboxylate, leading to a trigonal bipyramidal geometry, with the antimony-methyl groups in equatorial positions and the oxygen atoms in axial positions. The trimethylantimony compounds tested in vitro against a series of human tumour cell lines were found to be inactive.     

A high-performance liquid chromatography/tandem mass spectrometric screening method for eight synthetic corticosteroids in bovine feces and the simultaneous differentiation between dexamethasone and betamethasone

A screening method was developed to monitor the illegal use of synthetic corticosteroids in cattle. Diethyl ether extracts from spiked feces samples were cleaned-up by solid phase extraction followed by semipreparative reversed-phase chromatography (RPC). The fraction containing the corticosteroids was derivatized with ethoxyamine hydrochloride. The corresponding ethoximes were separated using silica-based C18 RPC and analyzed on-line in an ion trap mass spectrometer using atmospheric pressure positive chemical ionization. Ethoxime derivatives of dexamethasone and betamethasone were baseline resolved, allowing for the simultaneous mass spectrometric differentiation of both epimers in bovine feces by conventional non-chiral chromatography. At the lowest level tested (1 micro g/kg), corticosteroids (except triamcinolone) could be identified in compliance with the recent European criteria for residue identification. The quantitative performance of the method was best at residue levels > or = 2 micro g/kg.     

Exceptionally high in vitro antitumor activity of substituted triphenyltin benzoates including salicylates against a human mammary tumor,MCF-7, and a colon carcinoma,WiDr

Nine new substituted triphenyltin benzoates of the type Ar₃Sn? OOC? C₆H₂XYZ [X = Y = H, Z = 2-OCH₃ and 4-F; X = H, Y = 3-F, Z = 5-F; X = H, Y = 2-OH, Z = 5-Cl, 5-NH₂, 5-OCH₃ and 5-SO₃H; X = 2-OH, Y = 3-CH(CH₃)₂ and Z = 5-CH(CH₃)₂] were prepared and possess considerable in vitro antitumor activity against two human tumor cell lines (MCF-7, a mammary tumor, and WiDr, a colon carcinoma) comparable with that of mitomycin C.