Patent ID: 8716481

Claim:
A process for the preparation of a compound of formula (I) or a salt thereof, wherein n is 1, 2, 3 or 4; and R1 is H or a protecting group, comprising the steps of (A) reacting a compound of formula (II) wherein X is halogen, in a suitable solvent and in the presence of a base selected from a tertiary alkali metal alkoxide, alkali metal hydride or alkali metal with a compound of formula (III) wherein R1 is H or a protecting group and n is 1, 2, 3 or 4, to give a compound of formula (IV) wherein R1 is H or a protecting group and n is 1, 2, 3 or 4; and, if R1 is H, protecting the amino group to give a compound of formula (IV) wherein R1 is a amino protecting group; (B) reacting a compound of formula (IV) with a compound of formula (V) R 4 —CH[N(R 5 ) 2 ] 2 (V) wherein R 4 is —O(C 1 -C 6 )alkyl, and R 5 is (C 1 -C 6 )alkyl, to yield a compound of formula (VI) wherein R1 is a protecting group and n is 1, 2, 3 or 4; and (C) cyclizing a compound of formula (VI) and optionally removing the protecting group in a suitable solvent and in the presence of a hydrohalic acid to give a compound of formula (I) wherein R1 is H or a protecting group; (D) optionally removing the protecting group from a compound of formula (I) obtained in step (C), wherein R1 is a protecting group, to give compound a formula (I) wherein R1 is H, and (E) optionally converting a compound of formula (I) into a salt thereof.