A series of six new ferrocene-carbohydrate conjugates was prepared from pentose and hexose sugar derivatives. These include the ferrocenecarbaldehyde acetal 2, four ferrocenyltriazoles 4a-d derived from furanose sugar and the ferrocenyltriazole 4e derived from a pyranose sugar. The compounds were characterised by spectroscopic means and the structures of the new conjugates 2 and 4a were determined by means of X-ray crystallography. A UV/Vis study of these compounds performed in aqueous solutions under physiological conditions confirmed their stability. The CD spectral analysis shows the effect of the nature of substituents of the carbohydrate moieties. The electrochemical studies conducted in a buffer solution display one-electron reversible oxidation processes for these compounds. These results indicate that the compounds are suitable for conducting bio-[a]

Amide-triazole linker incorporated ferrocene-carbohydrate conjugates were prepared by adopting a regiospecific copper(II)-catalysed 1,3-cycloaddition of ferrocenoyl propargylamide and isopropylidene/acetyl protected carbohydrate azides. Hydrophilic ferrocene glycoside with an amide-triazole linker was synthesised by deacetylation of the hydroxyl groups. All the new compounds were characterised by UV-visible and electrochemical studies and they were found to be stable in organic solvents as well as in the buffer system under physiological conditions (pH = 7.0). The diffusion coefficient (D(f)) of the conjugates was also calculated by means of cyclic voltammetric studies. It was observed that while the molecular weight of the compounds had no significant effect on the diffusion coefficient, the hydrophobic/hydrophilic nature of the carbohydrate scaffold displayed varied diffusion coefficient values. Stabilization of the compounds in buffer solution under physiological pH led to almost identical diffusion coefficient values. The compounds derived from xylose and ribose exhibited cytotoxicity on hormone-dependent and hormone-independent breast cancer cell lines, whereas the conjugates derived from glucose and galactose were found to be non-toxic in nature. The compounds did not show any antimicrobial activity against Gram-positive and Gram-negative pathogens.

A series of four new ferrocene–carbohydrate amides was prepared from pentose and hexose sugar derivatives. These include (5‐amino‐5‐deoxy‐1,2‐O‐isopropylidene‐α‐d‐xylofuranose)‐1‐ferrocene carboxamide (2a), (5‐amino‐3‐O‐benzyl‐5‐deoxy‐1,2‐O‐isopropylidene‐α‐d‐xylofuranose)‐1‐ferrocene carboxamide (2b), (methyl‐6‐amino‐6‐deoxy‐2,3‐O‐isopropylidene‐β‐d‐ribofuranoside)‐1‐ferrocene carboxamide (2c) derived from furanose sugars and (6‐amino‐6‐deoxy‐1,2:3,4‐di‐O‐isopropylidene‐α‐d‐galactopyranose)‐1‐ferrocene carboxamide (2d) derived from pyranose sugar. The compounds were characterized by spectroscopic means and the structure of amide derived from α‐d‐xylofuranose (2a) was determined by X‐ray crystallography. The electronic and optical properties of the compounds were studied by means of cyclic voltammetry and absorption spectroscopy. The UV and electrochemical studies of these compounds, performed in aqueous solutions under physiological conditions (at pH 7.4), confirmed their stability. These results indicated that the compounds were suitable for conducting biological studies. The CD spectral analysis displays the effect of sugar substituents on the compounds. The cytotoxicity and antimicrobial activity of these conjugates were investigated on different cancer cell lines and microbes respectively. The degree of inhibition varied over a broad spectrum of Gram‐ positive and Gram‐negative bacteria. In addition, the compounds also exhibited antioxidant properties. Copyright © 2012 John Wiley & Sons, Ltd.

We report here an efficient protocol for the one-pot facile synthesis of spiro[indeno[1,2-b]quinoxaline-11,3′-pyrrolizine]heterocyclic scaffolds and their AChE inhibitory studies.

The reactions of the nitrile-stabilized complex [Re3(μ-H)3(CO)11(MeCN)] (1) and of the unsaturated complex [Re4(μ-H)4(CO)12] (2) with 2-amino-6-methylpyridine (Hampy), 2-mercaptopyridine (Hmerpy), and 2-hydroxy-6-methylpyridine (Hhympy) have been studied. Complex 1 reacts slowly with Hampy and Hmerpy (refluxing toluene, 5−7 h) to give the binuclear derivatives [Re2(μ-ampy)2(CO)6] (3) and [Re2(μ-merpy)2(CO)6] (4), but no reaction is observed between 1 and Hhympy under analogous conditions. Complex 2 reacts with Hampy and Hmerpy (refluxing 1,2-dichloroethane, 10−20 min) to give the trinuclear anionic derivatives [Re3(μ-H)3(μ3-ampy)(CO)9]- (5) and [Re3(μ-H)3(μ3-merpy)(CO)9]- (6), which have been isolated as pyridinium ([H2ampy]5) or triethylammonium ([HNEt3]5, [HNEt3]6) salts. Under analogous conditions, the reaction of 2 with Hhympy gives an inseparable mixture of compounds. The X-ray structures of [HNEt3]5 and [HNEt3]6 confirm that the three edges of the clusters are spanned by hydride ligands, that the ampy (in 5) and merpy (in 6) are attached to the three Re atoms, and that there are hydrogen-bonding interactions in the solid state between some carbonyl oxygen atoms and the NH fragments of the ampy ligand (in 5) and the triethylammonium cation (in 5 and 6).