Efficient and concise synthesis of βMan1-4GlcN linkage of pentasaccharide core by using 6-nitro-2-benzothiazolyl α-mannoside

Efficient and concise synthesis of βMan1-4GlcN of pentasaccharide core is established; direct β-mannosylations of 4-OH group of 2-deoxy-2-phthaloyl and 2-azide-2-deoxy glucose derivatives by using 6-nitro-2-benzothiazolyl α-mannoside proceeded smoothly to afford the desired β-mannosides in high yields.