A process for preparation of a compound of Formula wherein, R is C 1 -C 6 alkyl; R 1 is a hydroxyl-protecting group; and R 2 is hydrogen or fluorine; comprising: (a) converting a compound of Formula into a compound of Formula by treating the compound of Formula with an aqueous acid in the presence of a solvent at a temperature ranging from 0°C to 45°C for a period of 1 to 24 hours; (b) protecting a compound of Formula with a protecting group in the presence of a base in a solvent at a temperature ranging from 0°C to 45°C for a period of 2 to 6 hours to obtain a compound of Formula; (c) converting a compound of Formula into a 11,12 carbonate intermediate of Formula by reacting the compound of Formula with triphosgene in a solvent in the presence of a base; (d) oxidizing a compound of Formula into a compound of Formula by using a Corey-Kim oxidation with N-chlorosuccinimide-dimethyl sulphide or a Moffat oxidation with carbodiimide-dimethylsulphoxide complex in the presence of pyridinium trifluoroacetate or Dess-Martin periodinane; (e) converting a compound of Formula into a compound of Formula wherein R 2 is hydrogen by dissolving the compound of Formula in a solvent and by treating the compound of Formula with a strong base at a temperature ranging from 50°C to 80°C for 2 to 12 hours; and optionally converting a compound of Formula wherein R 2 is hydrogen to a compound of Formula wherein R 2 is fluorine by reacting the compound of Formula wherein R 2 is hydrogen with a fluorinating agent in the presence of a base and a solvent; (f) reacting a compound of Formula with chloroacetic anhydride or chloroacetic acid, optionally in the presence of a base, to obtain a compound of Formula wherein R 2 is hydrogen or fluorine; (g) reacting a compound of Formula with a cyanating agent in the presence of a base, to obtain a compound of Formula (VIII); and (h) reacting a compound of Formula (VIII) with hydroxylamine hydrochloride in the presence of a base to obtain a compound of Formula. R is C 1 -C 6 alkyl; R 1 is a hydroxyl-protecting group; and R 2 is hydrogen or fluorine; (a) converting a compound of Formula into a compound of Formula by treating the compound of Formula with an aqueous acid in the presence of a solvent at a temperature ranging from 0°C to 45°C for a period of 1 to 24 hours; (b) protecting a compound of Formula with a protecting group in the presence of a base in a solvent at a temperature ranging from 0°C to 45°C for a period of 2 to 6 hours to obtain a compound of Formula; (c) converting a compound of Formula into a 11,12 carbonate intermediate of Formula by reacting the compound of Formula with triphosgene in a solvent in the presence of a base; (d) oxidizing a compound of Formula into a compound of Formula by using a Corey-Kim oxidation with N-chlorosuccinimide-dimethyl sulphide or a Moffat oxidation with carbodiimide-dimethylsulphoxide complex in the presence of pyridinium trifluoroacetate or Dess-Martin periodinane; (e) converting a compound of Formula into a compound of Formula wherein R 2 is hydrogen by dissolving the compound of Formula in a solvent and by treating the compound of Formula with a strong base at a temperature ranging from 50°C to 80°C for 2 to 12 hours; and optionally converting a compound of Formula wherein R 2 is hydrogen to a compound of Formula wherein R 2 is fluorine by reacting the compound of Formula wherein R 2 is hydrogen with a fluorinating agent in the presence of a base and a solvent; (f) reacting a compound of Formula with chloroacetic anhydride or chloroacetic acid, optionally in the presence of a base, to obtain a compound of Formula wherein R 2 is hydrogen or fluorine; (g) reacting a compound of Formula with a cyanating agent in the presence of a base, to obtain a compound of Formula (VIII); and (h) reacting a compound of Formula (VIII) with hydroxylamine hydrochloride in the presence of a base to obtain a compound of Formula.