Patent ID: 7423146

Claim:
A process for making a compound of formula 1 or a salt thereof, wherein: R 1 and R 2 are each independently H, halogen, or C 1-4 -alkyl, or R 1 and R 2 together are C 1-6 -alkylene; and R 3 is H, halogen, OH, C 1-4 -alkyl, or O—C 1-4 -alkyl, the process comprising: (a) reacting a compound of formula 6 wherein R 4 is benzyl, diphenylmethyl, or trityl, each optionally substituted at, if available, an aryl group or an aliphatic carbon atom, with a compound of formula 7 or a salt thereof, to obtain a compound of formula 5, or a salt thereof (b) reducing the nitro group of the compound of formula 5 to an amine group and mesylating this amine group and cleaving the R 4 protecting group during the reduction step or after the mesylation step to obtain the compound of formula 1.