Processes for the preparation of SGLT-2 inhibitors, intermediates thereof

A process for preparing a compound (8), in desired R configuration, comprising:

• (a) reacting (S)-3-hydroxytetrahydrofuran with compound ii to form a compound iii;
• wherein R2 is C1-6 alkyl, trifluoromethyl or an aryl group optionally substituted at para position with halogen, nitro, or C1-6 alkyl;
• (b) treating the compound iii with an alkali metal acetate selected from the group consisting of lithium acetate, sodium acetate, potassium acetate and cesium acetate, optionally in the presence of a phase transfer catalyst to form a compound iv;
• wherein R2 is defined as hereinbefore;
• (c) subjecting the compound iv to hydrolysis to form a compound v, (R)-3-hydroxy tetrahydrofuran;
• (d) treating the compound v, (R)-3-hydroxytetrahydrofuran with compound ii to form the compound (8);
• wherein R2 is C1-6alkyl, trifluoromethyl or an aryl group optionally substituted at para position with halogen or C1-6 alkyl.

A process for preparing (1S)-1,5-anhydro-1-C-[4-chloro-3-[[4-[[(3S)-tetrahydro-3-furanyl]oxy]phenyl]methyl]phenyl]-D-glucitol, empagliflozin, wherein the process comprises:

• (a) reacting a compound of formula V with a compound B to obtain a compound of formula VI;
• wherein R1 is a hydroxyl protecting group selected from acetyl, propionyl, pivaloyl, and benzoyl;
• X is a leaving group selected from halogen, mesylate, tosylate, brosylate, besylate, nosylate and triflate;
• (b) coupling the compound of formula VI with tetrahydrofuran-3-ol (C) to obtain a compound of formula VIIa;
• (c) hydrolyzing the compound of formula VIIa to obtain a compound of formula VII;
• and
• (d) reducing the compound of formula VII to yield empagliflozin;