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Synthesis, molecular structure and cytotoxic activity of a series of 3-C, N, S, Se substituted benzo[b]selenophene derivatives on human fibrosarcoma HT-1080, mouse hepatoma MG-22A, and mouse fibroblasts 3T3 cell lines are described. The correlation between compound LD(50) 3T3 fibroblast cell line and HT-1080 morphology was shown., (Copyright © 2011 Elsevier Masson SAS. All rights reserved.)

Lithiation of 2-trimethylsilyl- and 2-trimethylgermylthiophenes by n -BuLi and subsequent silylation or germylation by dichlorodimethylsilane or dichlorodimethylgermane give bis[2-(5-trimethylsilyl-(germyl)thienyl]dimethylsilanes and -germanes ( 1a-d ). Their oxidation with 4 equivalents of m -chloroperbenzoic acid leads to formation of corresponding thiophene-1,1,1′1′-tetroxides ( 2a-d ). Nucleophilic addition of secondary amines to thiophene-1,1,1′1′-tetroxides ( 2a-d ) has been studied. It has been shown that the basicity of amine and the nature of solvent determine the reaction pathway. In water, the addition of two dimethylamine or piperidine molecules and only one diethylamine or morpholine molecule to each thiophene-1,1,1′1′- tetroxide fragment of the sulfone was accompanied by complete desilylation and degermylation. In organic solvents (benzene, THF) the addition of two piperidine molecules to each thiophen-1,1-dioxide fragment of bis[2-(5-trimethylsilyl)thienyl]dimethylsilane was observed. In this case the desilylation of both trimethylsilyl and dimethylsilyl groups occurred. [ABSTRACT FROM AUTHOR]

A series of thiophene-based homologues with a silicon core surrounded by mono-, bi-, terthiophene, and their derivatives with alkylsilyl linkages has been prepared using hydrosilylation and Stille coupling methods. [Copyright &y& Elsevier]

New furan and thiophene derivatives of aldimines o -HO-C 6 H 4 N CHC 4 H 4 X(R) (X = O, S; R = H, SiMe 3 , SiEt 3 , GeMe 3 , GeEt 3) were synthesized by condensation of o -aminophenol with the substituted aldehyde precursor. Their structure, electrochemical reduction/oxidation (in CH 3 CN/0.1 M Bu 4 NPF 6), frontier orbital energies, and cytotoxicity have been studied. Their electrochemical redox potentials E p show good correlation with the corresponding orbital energies and the difference E p ox – E p red corresponds well to their orbital hardness. These new compounds have a pronounced cytotoxicity toward cancer cells of human fibrosarcoma HT-1080 and mouse hepatoma MG-22A (IC 50 ≅ 1–8 μg ml−1) that can be modulated by introducing a Me 3 M substituent into the fifth position of the heterocycle (e.g., IC 50 (Me 3 Si)/IC 50 (H) ≥ 50). R 3 M-substitution reduces the orbital hardness of the aldimines studied and facilitates oxidation, promoting their oxidative metabolism. The neighboring group effect in the α-Me 3 Si-substituted thiophene derivative favors S-oxidation, which supposedly makes its metabolic mechanism different compared to R 3 M-substituted furan series (or for M = Ge in the thiophene series). Interestingly, SiMe 3 and GeMe 3 groups in both heterocyclic series (furan and thiophene) cause opposite trends in cytotoxicity, while the silyl group increases it, the germyl group decreases it. [ABSTRACT FROM AUTHOR]