Iron-Catalyzed Sonogashira Type Cross-Coupling Reaction of Aryl Iodides with Terminal Alkynes in Water under Aerobic Conditions

The first protocol for the iron-catalyzed Sonogashira type coupling of aryl iodides with terminal alkynes using exclusively water as the solvent under aerobic conditions is reported for the synthesis of diaryl alkynes. We found that the catalytic system comprised of FeCl3 center dot 6H(2)O and 1,10-phenanthroline is an efficient catalyst towards these coupling reactions. This methodology is applicable to a wide range of substituted aryl iodides with heteroaryl and sterically hindered groups and terminal aryl alkynes including heteroaryl alkynes with good yields. The present protocol provides economical and environmental advantages over other traditional methods due to the low cost and ecofriendly nature of the catalyst. Most importantly, the greenest solvent available, water, alone is used as the solvent for the first time for Iron-catalyzed Sonogashira type coupling reaction underlining the ecofriendly nature of the process.