Evdoxia Coutouli-Argyropoulou

Labeling of organic biomolecules with ethynylferrocene.

The Sonogashira coupling reaction of ethynylferrocene with adenine, uracil, tyrosine and steroid derivatives was studied; with the exception of tyrosine it was proved to be a good route for the attachment of ferrocene to these representative biomolecules. In addition the transformation of alkynyl uracil to furanopyrimidone derivatives was investigated and the formation of the furanopyrimidone ring was confirmed by an X-ray crystallographic analysis carried out on product 16.

Electrochemical studies of ferrocene derivatives and their complexation by β-cyclodextrin

The voltammetric behaviour of (ferrocenylmethyl)trimethylammonium hexafluorophosphate, 2-ferrocenylacrylic acid, N-ferrocenylmethyl-N′-methyl-4,4′-bipyridinium hexafluorophosphate and 9-ferrocenylmethyladenine was studied in aqueous and/or acetonitrile solutions by means of cyclic voltammetry and rotating-disc electrode voltammetry. The influence of β-cyclodextrin on the voltammetric behaviour of the compounds was also studied in aqueous solutions. (Ferrocenylmethyl)trimethylammonium hexafluorophosphate and 2-ferrocenylacrylic acid, studied in aqueous solutions at pH 9.2, exhibit typical reversible one electron transfer behaviour, whereas the redox reaction of 9-ferrocenylmethyladenine, studied in acetonitrile, is strongly affected by adsorption. N-ferrocenylmethyl-N′-methyl-4,4′-bipyridinium hexafluorophosphate gives voltammetric responses for both ferrocene and viologen redox centres in acetonitrile. In aqueous solutions it is hydrolyzed to ferrocenylmethylalcohol and N-methylbipyridyl, a process facilitated by the neighbouring group participation of the iron atom. In all cases β-cyclodextrin causes a decrease in the currents and shifts the potentials positively. The formation constants of the inclusion complexes of compounds with β-cyclodextrin were determined by quantitative evaluation of E1/2 values and possible explanations about their differentiation are discussed. In the case of N-ferrocenylmethyl-N′-methyl-4,4′-bipyridinium hexafluorophosphate it was found that β-cyclodextrin decreases the rate of its hydrolysis substantially.

Diastereocontrol in the intramolecular cycloadditions of 2-substituted-erythro-3,4-isopropylidenedioxyhex-5-enenitrile oxides

Abstract The influence of the 2-substituent on the diastereoselectivity of the intramolecular cycloadditions in a series of 2-substituted-erythro-3,4-isopropylidene-dioxyhex-5-enenitrile oxides, generated in situ from selected sugar derivatives, was examined.

Hetero-Diels–Alder additions to pent-4-enofuranosides: concise synthesis of hydroxylated pyrrolizidines

Abstract A new facile method for the synthesis of hydroxylated pyrrolizidines of the alexine family has been developed, which involves hetero-Diels–Alder addition of ethyl 2-nitrosoacrylate to pent-4-enofuranosides and a further two-step reductive ring opening-ring closure treatment of the cycloadduct.

A new entry to hydroxylated pyrrolizidines

Abstract A short and efficient synthesis of (1 R ,2 S ,5 R ,8 S )-5-hydroxymethyl-1,2-dihydroxypyrrolizidine 1 , by hetero -Diels–Alder addition of a nitrosoalkene to a pent-4-enofuranoside derived from D -ribose, followed by reductive opening of the oxazine ring formed, is reported.

Synthesis of unsymmetrical 1,1'-disubstituted ferrocenes. Formation of ferrocenophanes via intramolecular cycloaddition

Abstract Unsymmetrical 1,1′-disubstituted ferrocenes bearing appropriate substituents for intramolecular cycloadditions were synthesized conveniently starting from 1,1′-ferrocenedicarbaldehyde. Ferrocenenitrone derivatives reacted in an intramolecular regioselective manner affording ferrocenophanes.

Formation and reduction reactions of 3-indo-3-yl-isoxazolidines

Abstract 1,3-Dipolar cycloaddition reactions of C-(1-methylindol-3-yl)-N-methylnitrone (1 with carbonyl substituted dipolarophiles lead to the formation of indolyl-isoxazolidines 3–6. Further reduction of the cycloadducts bearing a 5-methoxycarbonyl substituent give the pyroolidinones 8, 10. The stereoselectivity of the reactions and the structure elucidation of the product are discussed.

An entry to new isoxazoline analogues of dideoxynucleosides by bromonitrile oxide 1,3-dipolar cycloaddition

A short and efficient synthesis of new isoxazolinyl nucleosides bearing the nucleobase at the 3-position is reported. The synthetic approach relies upon the 1,3-dipolar cycloaddition of bromonitrile oxide to allyl benzoate and subsequent substitution of the bromine by the nucleobase.

Bicyclo[3.1.0]hexanes from sugar-derived diazo compounds and iodonium ylides. Diastereocontrol and synthetic applications

Abstract The CuI and Rh 2 (OAc) 4 catalyzed decomposition of ethyl 2-diazo-4,5-isopropylidenedioxy-3-oxo-6-heptenoate results in intramolecular cyclopropanation products with opposite diastereoselectivity. In contrast, decomposition of the respective iodonium ylide can proceed without catalysts to give the cyclopropanation products with diastereoselectivity unchangeable by the presence of CuI and Rh 2 (OAc) 4 , revealing thus, that in this particular case the reaction is an electrophilic addition of the iodonium center to the double bond. The synthetic importance of these reactions has been demonstrated by preparing a number of precursors of cyclopentyl, cyclopropyl and bicyclo[3.1.0]hexyl antiviral carbocyclic nucleosides.

Electrochemical behaviour of N-methyl-N′-(3-indol-1-yl-propyl)-4,4′-bipyridinium. Anodic polymerization and redox properties of the viologen unit of monomer and polymer film

Abstract This article describes the synthesis and the electrochemical properties of a redox polymer, having a polyindole backbone and a viologen subunit, derived from the oxidative electropolymerization of N -methyl- N ′-(3-indol-1-yl-propyl)-4,4′-bipyridinium (In-V-Me 2+ ). Fairly stable films of poly(In-V-Me 2+ ) were obtained on Pt and Au electrodes from acetonitrile containing Et 4 NClO 4 as supporting electrolyte. The best films were grown on Au at potentials where electrodissolution of Au substrate occurs simultaneously with the electropolymerization. Poly(In-V-Me 2+ ) films show interesting electrochemical properties in acetonitrile and water which stem from the behaviour of the pendant viologen redox centres. The redox reactions of the monomer have also been studied. The indole viologen shows the usual behaviour of viologen compounds both in aqueous solutions and in acetonitrile. In aqueous solutions, In-V-Me 2+ forms on mercury monolayers of radical cations deposited at underpotentials with parallel and vertical orientation on the electrode surface.