Synthesis and NMR Characterization of Sophorosyl Trehalose Tetrasaccharides

Abstract

Glycosidation of 2′ 3′ 6′-tri-O-benzyl-α-d-glucopyranosyl 2,3-di-O-benzyl-4,6-O-benzylidene-α-d- glucopyranoside (2) with α-aceto-bromosophorose (1) gave the α- and β-linked tetrasaccharides 3 and 4 in an approximately 2:1 ratio in dichloromethane or acetonitrile. The reaction is discussed, notably the predominant formation of α-glycosides. Both compounds were fully characterized by ¹H and ¹³C NMR spectroscopy applying 1D TOCSY, 1D T-ROESY, ¹H-detected one-bond and multiple bond ¹H, ¹³C 2D COSY. Deprotection of 3 and 4 furnished the free sophorosyl trehaloses 7 and 8.