NOVEL OXIDATIVELY REMOVABLE PROTECTING GROUPS AND LINKERS FOR SOLID-PHASE SYNTHESIS OF OLIGOSACCHARIDES

Several new para-substituted benzyl- or phenyl-type protecting groups and their application to linkers for solid-phase synthesis are describ ed. p-Acylaminobenzyl groups have higher acid stability than the p-met hoxybenzyl (MPM) group, but are readily cleaved with 2,3-dichloro-5,6- dicyanobenzoquinone (DDQ). The p-azidobenzyl (Azb) group also has high er acid stability than the MPM group and can be removed much faster th an the MPM group by DDQ oxidation after conversion of the azide group into the corresponding iminophosphorane. The acid stability of the p-a zido-m-chlorobenzyl group (Cl-Azb) is higher than that of the Azb grou p. The former can be readily removed by DDQ oxidation after conversion of the azide group into the iminophosphorane. The p-acylaminophenyl g lycoside linker can be readily obtained from p-nitrophenyl glycoside a nd can be readily cleaved by ammonium cerium(IV) nitrate (CAN) oxidati on. This type of linker should be useful not only for the solid-phase synthesis of oligosaccharides but also for general solid-phase synthes is.