Krylov AS, Petrosian AA, Piterskaya JL, Svintsitskaya NI, Dogadina AV. Synthesis of ([1,2,4]triazolo[4,3-
a]pyridin-3-ylmethyl)phosphonates and their benzo derivatives via 5-
exo-
dig cyclization.
Beilstein J Org Chem 2019;
15:1563-1568. [PMID:
31354875 PMCID:
PMC6633597 DOI:
10.3762/bjoc.15.159]
[Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 07/03/2019] [Indexed: 11/25/2022] Open
Abstract
A series of novel 3-methylphosphonylated [1,2,4]triazolo[4,3-a]pyridines was accessed through a 5-exo-dig-type cyclization of chloroethynylphosphonates and commercially available N-unsubstituted 2-hydrazinylpyridines. In addition, 3-methylphosphonylated [1,2,4]triazolo[4,3-a]quinolines and 1-methylphosphonylated [1,2,4]triazolo[3,4-a]isoquinolines were synthesized in a similar manner. The presence of a NO2 group in the starting hydrazinylpyridine induces a Dimroth-type rearrangement leading to 2-methylphosphonylated [1,2,4]triazolo[1,5-a]pyridines.
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