Method for preparing 2'-o-fucosyllactose

A method for preparing 2′-O-fucosyllactose comprising the steps of

• a) reacting a fucose derivative of the general formula (I)
• where
• RSi are the same or different radicals of the formula SiRaRbRc, in which Ra, Rb and Rc are the same or different and are selected from C1-C8-alkyl, C3-C8-cycloalkyl, phenyl and C3-C8-cycloalkyl-C1-C4-alkyl;
• X is selected from the group consisting of Br and S-bound radicals, with a compound of the general formula (II)
• where
• R1 is a radical C(═O)—R11 or a radical SiR12R13R14, in which R11 is hydrogen, C1-C8-alkyl, C1-C8-haloalkyl, C3-C8-cycloalkyl, C3-C8-cycloalkyl-C1-C4-alkyl or phenyl, wherein said phenyl is unsubstituted or optionally has 1 to 5 substituents selected from the group consisting of halogen, CN, NO2, C1-C4-alkoxy, C1-C4-haloalkyl and C1-C4-haloalkoxy, and
• R12, R13 and R14 are the same or different and are selected from the group consisting of C1-C8-alkyl, C3-C8-cycloalkyl, phenyl and C3-C8-cycloalkyl-C1-C4-alkyl;
• R2 is the same or different and are C1-C8-alkyl, or two radicals R2 attached to the same carbon atom together form a linear C3-C6-alkanediyl, which is unsubstituted or has 1 to 6 methyl groups as substituents;
• R3 is the same or different and are C1-C8-alkyl or together form a linear C1-C4-alkanediyl, which is unsubstituted or has 1 to 6 methyl groups as substituents;
• in the presence of an activating reagent;
• and
• b) deprotecting the coupling product of the general formula (III) obtained in step a)
• where RSi, R1, R2 and R3 are as defined above;
• to obtain 2′-O-fucosyllactose.

A fucose derivative of the general formula (I)

• where
• RSi are the same or different radicals of the formula SiRaRbRc, in which Ra, Rb and Rc are the same or different and are selected from C1-C8-alkyl, C3-C8-cycloalkyl, phenyl and C3-C8-cycloalkyl-C1-C4-alkyl;
• X is selected from the group consisting of Br and S-bound radicals, namely —SCN, —S(O)n—RX1 or —S—RX2, where
• n is 0, 1 or 2,
• RX1 is aryl which is unsubstituted or optionally has 1 to 5 substituents selected from halogen, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-haloalkyl and C1-C4-haloalkoxy, and
• RX2 is selected from the group consisting of C1-C6-alkyl, C1-C6-haloalkyl, benzyl, wherein the phenyl moiety of benzyl is unsubstituted or optionally has 1 to 5 substituents selected from halogen, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-haloalkyl and C1-C4-haloalkoxy, and 5- or 6-membered heterocyclyl, which bears a nitrogen atom in ortho position relative to the point of attachment and optionally a second heteroatom selected from O and S in the other ortho position, where heterocyclyl may optionally carry a fused benzyl moiety;
• except for compounds of the formula (I), wherein
• RSi is trimethylsilyl, and X is —S-(4-methyl-phenyl),
• RSi is triethylsilyl, and X is —S-ethyl or —S(O)-phenyl, or
• RSi is tert-butyldimethylsilyl, and X is Br or —S-ethyl.