A process for the preparation of compounds of formula wherein Ring A and Ring B are one of the following: Ring A is an optionally substituted unsaturated monocyclic heterocyclic ring, and Ring B is an optionally substituted unsaturated monocyclic heterocyclic ring, an optionally substituted unsaturated fused heterobicyclic ring, or an optionally substituted benzene ring; or Ring A is an optionally substituted benzene ring, and Ring B is an optionally substituted unsaturated monocyclic heterocyclic ring, or an optionally substituted unsaturated fused heterobicyclic ring wherein Y is linked to the heterocyclic ring of the fused heterobicyclic ring; or Ring A is an optionally substituted unsaturated fused heterobicyclic ring, wherein the sugar moiety X-(sugar) and the moiety -Y-(Ring B) are both on the same heterocyclic ring of the fused heterobicyclic ring, and Ring B is an optionally substituted unsaturated monocyclic heterocyclic ring, an optionally substituted unsaturated fused heterobicyclic ring, or an optionally substituted benzene ring; X is a carbon atom; Y is -(CH 2) n -; wherein n is 1 or 2; provided that in Ring A, X is part of an unsaturated bond; or a pharmaceutically acceptable salt or solvate thereof; comprising reacting a compound of formula wherein Q 0 is bromo or iodo with a complex of di(C 1-4 alkyl)magnesium with lithium chloride or a complex of C 1-4 alkyl magnesium chloride with lithium chloride or a complex of C 1-4 alkyl magnesium bromide with lithium chloride; in an organic solvent or mixture thereof; at a temperature in the range of from ambient temperature to -78°C; to yield the corresponding compound of formula, wherein Q 1 is the corresponding MgCI or MgBr; reacting the compound of formula with a compound of formula, wherein Z is an oxygen protecting group selected from the group consisting of acetyl and pivaloyl; in an organic solvent or mixture thereof; at a temperature in the range of from ambient temperature to -78°C; to yield the corresponding compound of formula (XIII); reacting the compound of formula (XIII) with a Lewis acid; in the presence of a trialkylsilane; in an organic solvent or mixture thereof; at a temperature in the range of from 0°C to reflux; to yield the corresponding compound of formula; de-protecting the compound of formula; to yield the corresponding compound of formula. wherein Ring A and Ring B are one of the following: Ring A is an optionally substituted unsaturated monocyclic heterocyclic ring, and Ring B is an optionally substituted unsaturated monocyclic heterocyclic ring, an optionally substituted unsaturated fused heterobicyclic ring, or an optionally substituted benzene ring; or Ring A is an optionally substituted benzene ring, and Ring B is an optionally substituted unsaturated monocyclic heterocyclic ring, or an optionally substituted unsaturated fused heterobicyclic ring wherein Y is linked to the heterocyclic ring of the fused heterobicyclic ring; or Ring A is an optionally substituted unsaturated fused heterobicyclic ring, wherein the sugar moiety X-(sugar) and the moiety -Y-(Ring B) are both on the same heterocyclic ring of the fused heterobicyclic ring, and Ring B is an optionally substituted unsaturated monocyclic heterocyclic ring, an optionally substituted unsaturated fused heterobicyclic ring, or an optionally substituted benzene ring; Ring A is an optionally substituted unsaturated monocyclic heterocyclic ring, and Ring B is an optionally substituted unsaturated monocyclic heterocyclic ring, an optionally substituted unsaturated fused heterobicyclic ring, or an optionally substituted benzene ring; or Ring A is an optionally substituted benzene ring, and Ring B is an optionally substituted unsaturated monocyclic heterocyclic ring, or an optionally substituted unsaturated fused heterobicyclic ring wherein Y is linked to the heterocyclic ring of the fused heterobicyclic ring; or Ring A is an optionally substituted unsaturated fused heterobicyclic ring, wherein the sugar moiety X-(sugar) and the moiety -Y-(Ring B) are both on the same heterocyclic ring of the fused heterobicyclic ring, and Ring B is an optionally substituted unsaturated monocyclic heterocyclic ring, an optionally substituted unsaturated fused heterobicyclic ring, or an optionally substituted benzene ring; X is a carbon atom; Y is -(CH 2) n -; wherein n is 1 or 2;