Ethynylation of [1,2,4]Triazolo[1,5‐a]pyrimidinesUsing Substituted Ethynylmagnesium Bromides

Abstract

A series of [1,2,4]triazolo [1,5-a]pyrimidine-cored push-pull compounds, bearing ethynyl moieties, was effectively prepared using transition-metal-free strategy involving the direct CÀ H functionalization of [1,2,4]triazolo [1,5-a]pyrimidine scaffold with the Grignard-Iocich reagents (ethynylmagnesium bromides).The basic optical and electrochemical properties of the synthesized derivatives were studied and gave grounds to consider the obtained compounds as promising UV dyes with high quantum yields.

Recent Synthetic and Biological Developments on 1,2,4‐Triazolopyrimidines

“…Efficient construction of 6-bromo 27 or 6-phenyl[1,2,4]triazolo[1,5-a]pyrimidine (30) with high quantum yields has been demonstrated and subsequently then tethered with ethynyl group by employing metal-free CÀ H functionalization protocol involving ethyl-magnesium bromide reagent (Grignard-locich) (Scheme 6). [70] S. Akrami and co-workers reported a mild, environmentally benign, rapid, and regiospecific synthesis of chromeno [4,3- ). [71] The mechanism of reaction was believed to proceed initially with Knoevenagel condensation of 4hydroxycoumarin (38) and aldehyde followed by Michael addition reaction with 3-amino-1H-1,2,4-triazole (37), sequential intramolecular cyclization and dehydration to afford chromenotriazolo pyrimidines.…”

“…Efficient construction of 6‐bromo 27 or 6‐phenyl[1,2,4]triazolo[1,5‐a]pyrimidine ( 30 ) with high quantum yields has been demonstrated and subsequently then tethered with ethynyl group by employing metal‐free C−H functionalization protocol involving ethyl‐magnesium bromide reagent (Grignard‐locich) (Scheme 6). [70] …”