Synthesis of novel C-nucleoside analogues bearing an anomeric cyano and a 1,2,3-triazole nucleobase as potential antiviral agents.

A linear sequence to access a novel series of C-nucleosides bearing a quaternary carbon at the anomeric position tethered to a 4-substituted 1,2,3-triazole ring is described. Most of the compounds were obtained from a C-1 alkynyl furanoside, by a tandem or two-step CuAAC/functionalisation sequence, along with a diastereoselective cyanation of the furanoside derivatives in acidic conditions.

From Oxygen to Sulfur and Back: Difluoro -H-phosphinothioates as a Turning Point in the Preparation of Difluorinated Phosphinates: Application to the Synthesis of Modified Dinucleotides.

A simple, two-step procedure to convert α,α-difluorinated H-phosphinic acids into the corresponding H-phosphinothioates is described. The usefulness of these species is demonstrated by their transformation into difluorinated phosphinothioyl radicals and their addition onto alkenes. Additionally, sequential treatment of H-phosphinothioates by a strong base and a primary alkyl iodide constitutes an alternate route to the formation of the C-P bond. Both methods efficiently deliver difluorinated phosphinothioates. Similar reactions carried out with the fully oxygenated counterparts clearly indicate the superiority of the sulfur-based species and emphasize the crucial role played by sulfur in the construction of the second C-P bond. Oxidation easily transforms the thereby obtained phosphinothioates into the corresponding phosphinates. The whole strategy is applied to the stereoselective preparation of dinucleotide analogues featuring either a difluorophosphinothioyl or a difluorophosphinyl unit linking the two furanosyl rings.

Diastereoselective access to trans-2-substituted cyclopentylamines.

A highly diastereoselective synthesis of trans-2-substituted cyclopentylamines via a tandem hydrozirconation/Lewis acid-mediated cyclization sequence applied to butenyl oxazolidines is described. The method allows an easy preparation of diversely substituted cyclopentylamines which appear to be useful synthetic intermediates. This was further illustrated by the syntheses of (±)-Rodocaine, (±)-trans-pentacin, and enantiomerically enriched trans-cyclopentane-1,2-diamine.