Pd/Ligand-Free Synthesis of 2-Alkynylated Pyrano[4,3-<i>d</i>]imidazol-4-ones via One-Pot Cu-Mediated Tandem Sonogashira Coupling/Regioselective 6-<i>endo</i>-<i>dig</i> Oxacyclization Reaction.

ABSTRACT: Herein, we report a one-pot palladium- and ligand-free tandem Sonogashira coupling/regioselective 6-endo-dig oxacyclization reaction of 2,4-diiodo-1-methyl-imidazole-5-carboxylic acid with terminal alkynes mediated by Copper(I). This impressive approach offers a straightforward, practical, and efficient tandem procedure for accessing 2-alkynylated pyrano[4,3-d]imidazol-4-one in moderate to good yields with an exclusive 6-endo-dig oxacyclization. Notably, this cost-effective methodology demonstrates broad substrate compatibility with various commercially available aliphatic and (hetero)aromatic terminal alkynes. Furthermore, DFT studies were performed to elucidate the origin of this regioselective 6-endo-dig oxacyclization reaction.

SUBMITTER: Ayachi A 

PROVIDER: S-EPMC12300436 | biostudies-literature | 2025 Jul

REPOSITORIES: biostudies-literature