Solid-phase chemoenzymatic synthesis of C-sialosides

From polymer to small organic molecules: a tight relationship between radical chemistry and solid-phase organic synthesis

Since Gomberg's discovery of radicals as chemical entities, the interest around them has increased through the years. Nowadays, radical chemistry is used in the synthesis of 75% of all polymers, inevitably establishing a close relationship with Solid-Phase Organic Synthesis. More recently, the interest of organic chemists has shifted towards the application of usual "in-solution" radical chemistry to the solid-phase, ranging from the use of supported reagents for radical reactions, to the development of methodologies for the synthesis of small molecules or potential libraries. The aim of this review is to put in perspective radical chemistry, moving it away from its origin as a synthetic means for solid supports, to becoming a useful tool for the synthesis of small molecules.

Synthesis of a library of fucopyranosyl-galactopyranosides consisting of a complete set of anomeric configurations and linkage positions

A library composed of a complete set of fucopyranosyl-galactopyranosides was synthesized. A perbenzylated phenylthio fucopyranoside and a series of tri-O-benzyl-galactopyranosyl fluorides having single hydroxyl groups at the 2-, 3-, 4-, and 6-positions were used as the glycosyl donor and glycosyl acceptors, respectively. The chosen set of functionalities at the anomeric centers enabled rapid access to the oligosaccharides based on chemoselective activation. The first coupling reaction was achieved by the action of dimethyl(methylthio)sulfonium trifluoromethanesulfonate (DMTST). The resulting disaccharide fluoride was readily activated by hafnocene bistrifluoromethanesulfonate [Cp2Hf(OTf)2] and glycosidated with n-octanol.

Lanthanide reagents in solid phase synthesis

From solid-supported ytterbium(III) catalysts to linkers cleaved by electron transfer from samarium(II) species, lanthanide reagents are beginning to find widespread application in solid phase organic synthesis. This tutorial review introduces the use of lanthanide(III) Lewis acids and lanthanide(IV) oxidants in solid phase chemistry before concentrating on the growing use of lanthanide(II) reagents in the area.

Evaluation of a new linker system cleaved using samarium(ii) iodide. Application in the solid phase synthesis of carbonyl compounds

A new linker design for solid phase synthesis has been developed that is cleaved under mild, neutral conditions using samarium(II) iodide. The feasibility of the linker approach has been illustrated in the solid phase synthesis of ketones and amides using an oxygen linker. Insights into the mechanism of the samarium(II) iodide cleavage reaction are described and the potential of a sequential cleavage carbon-carbon bond forming process is assessed.