Convergent synthesis of a tetrasaccharide repeating unit of the O-specific polysaccharide from the cell wall lipopolysaccharide of Azospirillum brasilense strain Sp7

• Pintu Kumar Mandal,
• Debashis Dhara and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2014, 10, 293–299, doi:10.3762/bjoc.10.26

• -700054, India 10.3762/bjoc.10.26 Abstract A straightforward convergent synthesis has been carried out for the tetrasaccharide repeating unit of the O-specific cell wall lipopolysaccharide of the strain Sp7 of Azospirillum brasilense. The target tetrasaccharide has been synthesized from suitably

• protected monosaccharide intermediates in 42% overall yield in seven steps by using a [2 + 2] block glycosylation approach. Keywords: Azospirillum brasilense; glycosylation; lipopolysaccharide; plant growth-promoting bacteria (PGPB); tetrasaccharide; Introduction The intensive use of chemicals for the

• be among the most promising ones [1]. Azospirillum brasilense (A. brasilense) is a plant growth-promoting bacterium, found abundant in the rizosphere of several leguminous plants and regular crops such as wheat, rice, corn etc. Azospirillum is a Gram-negative rizobacterium, which exerts a variety of