Patent ID: 6979723

Claim:
A process for preparing a compound of formula I: wherein R 1 is selected from the group consisting of C 1-10 alkylene, C 2-10 alkenylene and C 2-10 alkynylene; R 2 is selected from the group consisting of C 1-20 alkyl, C 2-20 alkenyl, C 2-20 alkynyl, C 3-8 cycloalkyl, C 5-8 cycloalkenyl, C 6-10 aryl, C 2-9 heteroaryl, C 2-9 heterocyclic, —R a —Cy 1 , —R a —Ar 1 —Ar 2 , —R a —Ar 1 —R b —Ar 2 , —R a —Ar 1 —O—R b —Ar 2 ; R 4 is C 1-10 alkylene; R a is selected from the group consisting of C 1-10 alkylene, C 1-10 alkenylene and C 1-10 alkynylene; R b is selected from the group consisting of C 1-6 alklene, C 1-6 alkenylene and C 1-6 alkynylene; Cy 1 is selected from the group consisting of C 2-8 cycloalkyl, C 5-8 cycloalkenyl, C 6-10 aryl, C 2-9 heteroaryl, C 2-9 heterocyclic; Ar 1 and Ar 2 are independently selected from C 6-10 aryl and C 2-9 heteroaryl; wherein each aryl, heteroaryl and heterocyclic group is optionally substituted with 1 to 3 substituents independently selected from the group consisting of C 1-6 alkyl, C 1-6 alkoxy, halo, hydroxy, nitro and trifluoromethyl, and each heteroaryl and heterocyclic group contains from 1 to 3 heteroatoms selected from nitrogen, oxygen or sulfur; or a salt thereof; the process comprising: (a) reacting vancomycin or a salt thereof, with a compound of formula II: wherein R 1 and R 2 are as defined herein; and R 3 is a amine-labile protecting group; and a reducing agent to form a compound of formula III: wherein R 1 , R 2 and R 3 are as defined herein, or a salt thereof; (b) reacting the compound of formula III with an amine to provide a compound of formula IV: wherein R 1 and R 2 are as defined herein, or a salt thereof; wherein step (a) and step (b) are conducted in the same reaction mixture without isolation of the intermediate from step (a). (c) reacting the compound of formula IV with formaldehyde and a compound of formula V: in the presence of a base to provide a compound of formula I, or a salt thereof.