A process is provided for the preparation of a key intermediate in the preparation of 2'-branched nucleoside compounds. The process includes contacting a protected precursor 3,4-O-isopropylidene-2-C-substituted-D-arabinono-1,5-lactone with a fluorinating agent under anhydrous conditions and converting the precursor into a protected 2-deoxy-2-halo-2-C-disubstituted ribono-1,5-lactone and optionally into a 2-deoxy-2-halo-2-C-disubstituted ribono-1,4-lactone.