Palladium-catalyzed chemoselective monoarylation of hydrazides for the synthesis of [1,2,4]triazolo[4,3-a]pyridines.
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.
Reichelt
Andreas
A
Department of Medicinal Chemistry, Amgen, Inc., One Amgen Center Drive, Thousand Oaks, California 91320-1799, USA. andreas.reichelt@amgen.com
Falsey
James R
JR
Rzasa
Robert M
RM
Thiel
Oliver R
OR
Achmatowicz
Michal M
MM
Larsen
Robert D
RD
Zhang
Dawei
D
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
D006834:Hydrazines; D011725:Pyridines; D014230:Triazoles; D010165:Palladium; C083126:2-chloropyridine; D019342:Acetic Acid