Patent ID: 8093354

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 , and —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 alkylene, C 1-6 alkenylene and C 1-6 alkynylene; Cy 1 is selected from the group consisting of C 3-8 cycloalkyl, C 5-8 cycloalkenyl, C 6-10 aryl, C 2-9 heteroaryl, and 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 and 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 at a temperature in the range from about −20° C. to about 20° C. to provide a compound of formula I, or a salt thereof.