Synthesis of ([1,2,4]triazolo[4,3-a]pyridin-3-ylmethyl)phosphonates and their benzo derivatives via 5-exo-dig cyclization

• Aleksandr S. Krylov,
• Artem A. Petrosian,
• Julia L. Piterskaya,
• Nataly I. Svintsitskaya and
• Albina V. Dogadina

Beilstein J. Org. Chem. 2019, 15, 1563–1568, doi:10.3762/bjoc.15.159

• reaction mixture after the complete conversion of chloroethynylphosphonate promotes a Dimroth-like rearrangement of [1,2,4]triazolo[4,3-a]pyridine 10 into [1,2,4]triazolo[1,5-a]pyridine 12 completely (Scheme 4). Similar transformations have been observed in the reactions of 2-hydrazinylpyridines with ethyl

New approach toward the synthesis of deuterated pyrazolo[1,5-a]pyridines and 1,2,4-triazolo[1,5-a]pyridines

• Aleksey Yu. Vorob’ev,
• Vyacheslav I. Supranovich,
• Gennady I. Borodkin and
• Vyacheslav G. Shubin

Beilstein J. Org. Chem. 2017, 13, 800–805, doi:10.3762/bjoc.13.80

• An efficient and operationally simple synthesis of 7-deuteropyrazolo[1,5-a]pyridine and 7-deutero-1,2,4-triazolo[1,5-a]pyridine derivatives using α-H/D exchange of 1-aminopyridinium cations in basic D2O followed by a 1,3-cycloaddition of acetylenes and nitriles is presented. A high regioselectivity

• and a high degree of deuterium incorporation were achieved. The procedure was applied for several 4-R-1-aminopyridinium cations (R = H, Me, OMe). Keywords: deuteration; 1,3-dipolar cycloaddition; pyrazolo[1,5-a]pyridine; 1,2,4-triazolo[1,5-a]pyridine; Introduction Isotopically labeled compounds find

• years deuteration became also an efficient tool in drug design [6]. Pyrazolo[1,5-a]pyridine and 1,2,4-triazolo[1,5-a]pyridine scaffolds attracted significant attention to the medicinal chemistry community during the past decade. For example, pyrazolo[1,5-a]pyridine derivatives were used in the design of