title: Palladium-catalyzed chemoselective monoarylation of hydrazides for the synthesis of [1,2,4]triazolo[4,3-a]pyridines.
abstract: An efficient and convenient method for the synthesis of [1,2,4]triazolo[4,3-a]pyridines was exemplified by the synthesis of 20 analogues bearing a variety of substituents at the 3-position. The methodology involves a palladium-catalyzed addition of hydrazides to 2-chloropyridine, which occurs chemoselectively at the terminal nitrogen atom of the hydrazide, followed by dehydration in acetic acid under microwave irradiation.
authors.affiliation: Department of Medicinal Chemistry, Amgen, Inc., One Amgen Center Drive, Thousand Oaks, California 91320-1799, USA. andreas.reichelt@amgen.com
authors.forename: Andreas
authors.initials: A
authors.lastname: Reichelt
authors.forename: James R
authors.initials: JR
authors.lastname: Falsey
authors.forename: Robert M
authors.initials: RM
authors.lastname: Rzasa
authors.forename: Oliver R
authors.initials: OR
authors.lastname: Thiel
authors.forename: Michal M
authors.initials: MM
authors.lastname: Achmatowicz
authors.forename: Robert D
authors.initials: RD
authors.lastname: Larsen
authors.forename: Dawei
authors.initials: D
authors.lastname: Zhang
mesh_terms: D019342:Acetic Acid / Q000737:chemistry; D002384:Catalysis; D020650:Combinatorial Chemistry Techniques; D003500:Cyclization; D006834:Hydrazines / Q000737:chemistry*; D008872:Microwaves; D015394:Molecular Structure; D010165:Palladium / Q000737:chemistry*; D011725:Pyridines / Q000138:chemical synthesis* / Q000737:chemistry*; D014230:Triazoles / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D006834:Hydrazines; D011725:Pyridines; D014230:Triazoles; D010165:Palladium; C083126:2-chloropyridine; D019342:Acetic Acid