Oligosaccharide C-glycoside derivatives

A process for preparing a compound of I-1

• wherein the compound of formula I-1 is a single diastereomer of the following β-anomer:
• or an amount of the β-anomer to an amount of an α-anomer (β-anomer:α-anomer) of the compound of formula I-1 is >10:1,
• or a pharmaceutically acceptable salt thereof,
• the process comprising:
• reacting a compound of formula II
• with a compound of formula III
• in the presence of at least one primary or secondary amine and at least one additive selected from the group consisting of:
• (a) pyrrolidine and H3BO3,
• (b) pyrrolidine and B(OMe)3, and
• (c) benzylamine and H3BO3,
• to give a compound of formula I
• wherein the compound of formula I is a single diastereomer of the following β-anomer:
• or an amount of the β-anomer to an amount of an α-anomer (β-anomer:α-anomer) of the compound of formula I is >10:1, and
• reacting the compound of formula I with a reactant to prepare the compound of I-1, wherein
• X is C1-7alkyl, C3-7cycloalkyl, halo-C1-7alkyl, C1-7alkoxy, halo-C1-7alkoxy, C1-7alkoxy-C1-7alkyl, (C1-7alkoxycarbonyl)-C1-7alkyl, C2-7alkynyl-C1-7alkyl, or aryl, which are optionally substituted,
• R1 is H, or a sugar residue,
• R2 is H, or a sugar residue, and
• R3 is H, or a sugar residue,
• R4 and R5 independently from each other are selected from the group consisting of H, C1-7alkyl, phenyl, benzyl, piperidinyl, p-tosyl, and 1-phthalazinyl, wherein the C1-7alkyl, phenyl, benzyl, piperidinyl, p-tosyl, and 1-phthalazinyl are optionally substituted.