Nucleoside analogues with a 1,3-diene-Fe(CO)3 substructure: Stereoselective synthesis, configurational assignment, and apoptosis-inducing activity

Abstract

The synthesis and stereochemical assignment of two classes of iron-containing nucleoside analogues, both of which contain a butadiene-Fe(CO)3 substructure, is described. The first type of compounds are Fe(CO)3-complexed 3'-alkenyl-2′,3′-dideoxy- 2′,3′-dehydro nucleosides (2,5-dihydrofuran derivatives), from which the second class of compounds is derived by formal replacement of the ring oxygen atom by a CH2 group (carbocyclic nucleoside analogues). These compounds were prepared in a stereoselective manner through the metal-assisted introduction of the nucleobase. Whilst the furanoid intermediates were prepared from carbohydrates (such as methyl-glucopyranoside), the carbocyclic compounds were obtained by using an intramolecular Pauson-Khand reaction. Stereochemical assignments based on NMR and CD spectroscopy were confirmed by X-ray structural analysis. Biological investigations revealed that several of the complexes exhibited pronounced apoptosis-inducing properties (through an unusual caspase 3-independent but ROS-dependent pathway). Furthermore, some structure-activity relationships were identified, also as a precondition for the design and synthesis of fluorescent and biotin-labeled conjugates. I gotta Fe-ling: Iron-containing nucleoside analogues, which were first synthesized during an exercise in stereoselective π-complex chemistry, exhibited pronounced cytotoxic and apoptosis-inducing activities, even against resistant cancer cell lines. Both hetero- (X=O) and carbocyclic (X=CH2) compounds were studied, and a synthetic route to R′-labeled derivatives was developed as a precondition for future biological experiments. TDS=thexyldimethylsilyl. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.