Maria N. Bakola-Christianopoulou

Metallkomplexe funktioneller Isocyanide: XV. [3 + 2]-Cycloadditionen von freiem und komplexgebundenem Isocyanmethylenphosphoran mit Heteroallenen☆

Abstract The metallo-nitrile ylides (M  Cr, W) react with CS2, methyl isocyanate and phenyl isothiocyanate regio- and site-specifically to give carbenoid five-membered heterocycles containing the structural element of a vinyl analogous phosphine oxide (sulfide). In addition, an (exoS-coordinated isomer was observed in one case. the exo-sulfur atom has been methylated and has been introduced into a platinum(II) complex. Analogous reactions have been carried out with “free” isocyanomethylene triphenylphosphorane and found to proceed far less cleanly. The reasons for that are discussed.

Synthesis and studies of some bivalent metal chelates of 1,2-dihydroxy-9,10-anthracenedione and 5-hydroxy-1,4-naphthalenedione

Abstract The chelates of 1,2-dihydroxy-9,10-anthracenedione and 5-hydroxy-1,4-naphthalenedione have been prepared and studied. The structure and bonding of these compounds are discussed in relation to their spectroscopic and magnetic data.

Synthesis, Spectroscopy and in vitro Cytotoxicity of New Hydroxyanthraquinonato Triorganotin Compounds

We will present herein data on the synthesis, structural investigation and in vitro antitumor activity of new triorganotin compounds of the general type (R3Sn)2Q, where R=Bu, Ph, Bz, Q1=1,4‐dihydroxy‐9,10‐anthracenedione (quinizarin), Q2=1,5‐dihydroxy‐9,10‐anthracenedione (anthrarufin), Q3=2,3‐dihydro‐9,10‐dihydroxy‐1,4‐anthracenedione (leucoquinizarin) and R3SnQ 4 where Q4=1,2‐dihydroxy‐9,10‐anthracenedione (alizarin). The compounds were synthesized by refluxing the organotin hydroxide with the parent quinone and were characterized by IR, 1H‐ NMR and thermal measurements. The spectroscopic analysis of the new triorganotins, provides evidence on the formation of a monodentate Sn‐O bond for quinizarin, anthrarufin and leucoquinizarin, which are coordinated to Sn(IV) central atom via the phenolic oxygen donor atoms, with the R‐substituents of the organotin moiety completing the tetrahedral coordination environment. On the contrary, organotin alizarinates form a six‐membered chelate ring, which stabilizes the Sn central atom in a five‐coordinated environment exhibiting distorted trigonal bipyramidal geometry. The ligand is coordinated to Sn (IV) via the quinoidal oxygen and its neighbouring phenolic one. The new compounds were tested for their cytotoxicity against human tumor and normal cell lines and the results are reported.

Chemical Aspects of Organotin Derivatives of Beta‐diketones, Quinonoids, Steroids and Some Currently Used Drugs: A Review of the Literature with Emphasis on the Medicinal Potential of Organotins

The last 50–70 years there has been an increasing interest on organotin compounds mainly because of their industrial, agricultural and biological applications. This review aims to offer a substantial overview of the organotin complexes of beta‐diketones and beta‐diketone derivatives, quinonoids, steroids and NSAIDs describing their structure, coordination mode and properties. Discussion will be focused on the interaction of organotins with endocrine systems and especially on their ability to interfere with sex steroid hormones and relative enzymes as well as with their current status as potential therapeutics for malignancies, inflammations, and infections.

Reductive hydrosilylation of quinones catalyzed by tris(triphenylphosphine) chlororhodium(I)

Abstract Tris(triphenylphosphine)chlororhodium(I) has been found to be an effective catalyst for the homogeneous reductive hydrosilylation of quinones. The reactions offer an easy procedure for protecting the highly reactive quinonic moiety of naturally-occurring and biologically-important macromolecules.

Synthesis, Structure and In vitro Biological Activity of New Hydroxy‐Naphthoquinonato Triorganotin Compounds

We report herein on the synthesis, structure and in vitro antitumor activity of new triorganotin compounds of the general type (R3Sn)nL, where R=Me, Bu, Ph, Bz; L1=5‐Hydroxy‐1,4‐naphthoquinone; L2=2‐Hydroxy‐1,4‐naphthoquinone; L3=5,8‐dihydroxy‐1,4‐naphthoquinone; n=1 for L1 & L2 n=2 for L2 and L3. The compounds were synthesized by reacting the triorganotin hydroxide with the parent hydroxy‐quinone and were characterized by IR, 1H‐, NMR, and thermal measurements. The spectroscopic analysis provides evidence on the formation of a chelate ring that is responsible for the stabilization of the triorganotin cation with the Sn central atom in a five‐coordinated environment exhibiting distorted trigonal bipyramidal geometry. The new compounds were tested for their cytotoxicity against five human tumor cell lines and one non‐tumor human cell line and the results are reported.

GC–SIM/MS Profiling of Urinary Steroids as their Per‐trimethylsilyl Derivatives

Complete GC–SIM/MS separation and identification of 19 steroids (including several steroid isomers) in a male urine sample, as their per-trimethylsilyl ethers, is described. Trimethylsilylation of their functional groups (hydroxyl and carbonyl) was achieved by a rapid, simplified and one-step derivatization method, using N-methyl-N-trimethylsilyl-2,2,2,-trifluoroacetamide as the silylating agent and the solvent as well, along with catalytic amounts of trimethylsilyl iodide and dithioerythritol. Furthermore, a GC/MS method for the analysis of a synthetic mixture of underivatized urinary steroids is proposed.

SYNTHESIS OF HYDROLYTICALLY STABLE tert-BUTYLDIMETHYLSILYL ETHERS OF HYDROXYANTHRAQUINONES

Abstract A series of hydrolytically stable hydroxyanthraquinone tert-butyldimethylsilyl ethers was synthesized by hydroxyl group silylation, under optimized reaction conditions. Tert-butyldimethylsilylchloride and N-methyl-N-tert-butyldimethylsilyl-1,1,1-trifluoroacetamide were each used as the silylating agent in two different silylating procedures. The products were studied by several chromatographic and spectroscopic techniques (TLC, GC, MS, IR, UV-Vis, 1H NMR). Some helpful notifications for the advantageous use of each procedure, in regard to the requirements of the application field, were also made.

A new method of bile acid silylation for their GLC-MS analysis

The trimethylsilyl (TMS) derivatives of a mixture of nine bile acids (six free and three conjugated), namely lithocholic, deoxycholic, chenocholic, cholic, hyodeoxycholic, ursodeoxycholic, glycodeoxycholic, glycocholic and glycochenodeoxycholic acids, have been prepared by a new, simple, efficient derivatization procedure, based on the use of a mixture of N-methyl-N-trimethylsilyl-1,1,1- trifluoroacetamide and 1-(trimethylsilyl)imidazole, as the silylating agent. The above-mentioned bile acids were completely trimethylsilylated on all hydroxyl and carboxyl groups whereas carbonyl and amino groups remained untouched.

Desilylation of t-butyldimethylsilyl ethers of hydroxyquinones

Desilylation of a series of hydrolytically stable hydroxyquinone t-butyldimethylsilyl ethers was achieved in high yields by the use of potassium fluoride in the presence of catalytic amounts of aqueous 48% hydrobromic acid (HBr), or basic aluminium oxide (Al 2 O 3 ), and tetra-n-butylammonium fluoride (Bu 4 NF) as cleaving agents.