Synthesis of a cyclic tetramer of 3-amino-3-deoxyallose with axially oriented amino groups

A linear tetramer of beta-(1 -> 6)-linked 3-azido-3-deoxy-D-allose containing glycosyl donor and glycosyl acceptor functions in the terminal monosaccharide units was prepared starting from 3-azido-3-deoxy-1,2:5,6-di-O-isopropylidene-alpha-D-allofuranose. Cyclization of the linear tetramer under glycosylation conditions afforded the corresponding cyclic tetrasaccharide in 77% yield; its deprotection and reduction of the azido groups resulted in the formation of the cyclic tetramer of 3-amino-3-deoxy-D-allose with axial amino groups, a potential scaffold for the synthesis of tetravalent functional clusters.