Di- and trisaccharide thioglycoside building blocks, Et (2,3,4-tri-O-benzyl-b-D-xylopyranosyl)-(1->2)-3-O-allyl-4,6-di-O-benzyl-1-thio-a-D-mannopyranoside, Et (2,3,4-tri-O-benzyl-b-D-xylopyranosyl)-(1->2)-6-O-acetyl-3-O-allyl-4-O-benzyl-1-thio-a-D-mannopyranoside and Et (2,3,4-tri-O-benzyl-b-D-xylopyranosyl)-(1->4)-[(2,3,4-tri-O-benzyl-b-D-xylopyranosyl)-(1->2)]-3-O-allyl-6-O-benzyl-1-thio-a-D-mannopyranoside, corresponding to repetitive structures in the capsular polysaccharide (CPS) of Cryptococcus neoformans have been synthesized using silver triflate-promoted couplings between benzobromoxylose and properly protected mannose Et thioglycosides. The blocks contain an orthogonal allyl group in the 3-position of the mannose residue to allow continued formation of the (1->3)-linked mannan backbone of the CPS. They have benzyl ethers as persistent protecting groups to facilitate access to the acetylated target structures. Assembly of the blocks employing DMTST as promoter in di-Et ether afforded in high yield and complete stereoselectivity penta- and hexasaccharide motifs from C. neoformans serotype A-C. The latter were deallylated into new acceptors to allow synthesis of larger CPS-fragments. [on SciFinder (R)]