Sonogashira-Hagihara Coupling towards Diaryl Alkynes Catalyzed by FeCl3⋅6 H2O/Cationic 2,2'-Bipyridyl

• Published in: ChemCatChem Vol. 4; no. 4; pp. 540 - 545
• Main Authors: Hung, Tzu-Ting, Huang, Chun-Min, Tsai, Fu-Yu
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.04.2012; WILEY‐VCH Verlag
• Subjects: cations; cross-coupling; green chemistry; homogeneous catalysis; iron
• ISSN: 1867-3880; 1867-3899
• DOI: 10.1002/cctc.201100358

Efficient and environmentally benign one‐pot Sonogashira–Hagihara coupling of aryl iodides with 4‐aryl‐2‐methylbut‐3‐yn‐2‐ols catalyzed by an FeCl3⋅6 H2O/cationic 2,2'‐bipyridyl system in water under air in the presence of zinc powder reductant was performed. Various aryl iodides and 4‐aryl‐2‐methylbut‐3‐yn‐2‐ols were used as reactants, which afforded moderate to high yields of cross‐coupled products. Although alkyl‐substituted 2‐methylbut‐3‐yn‐2‐ol could not be coupled with aryl iodides, the use of alkyl terminal alkynes under similar conditions provided the corresponding products in moderate yields. This reaction protocol was also used to synthesize both symmetric and asymmetric 1,4‐diarylbuta‐1,3‐diynes. This one‐pot iron‐catalyzed Sonogashira–Hagihara coupling reaction progressed without the use of an organic solvent, a copper cocatalyst, or an inert atmosphere, rendering it an environmentally friendly method with potential for practical applications. Coupling in one pot: The coupling of aryl iodides and 4‐aryl‐2‐methylbut‐3‐yn‐2‐ols in water is catalyzed by an FeCl3⋅6 H2O/cationic 2,2'‐bipyridyl system, which gives diaryl alkynes. This one‐pot iron‐catalyzed Sonogashira–Hagihara coupling progresses without the use of an organic solvent, a copper cocatalyst, or an inert atmosphere, rendering it an environmentally friendly method.