Pd-EnCat™ TPP30 as a Catalyst for the Generation of Highly Functionalized Aryl- and Alkenyl-Substituted Acetylenes via Microwave-Assisted Sonogashira Type Reactions

We report a rapid microwave-assisted Sonogashira cross-coupling of aryl iodides and bromides with terminal alkynes using Pd-EnCat(TM) TPP30. Both electron-rich and electron-deficient aryl halides reacted smoothly with a broad variety of terminal alkynes in MeCN at 100-120 degrees C. The coupling products were obtained in good to excellent yields and in high purity. This reaction can be performed under copper- and DMF-free conditions and does not require an inert atmosphere. Furthermore, the encapsulated catalyst can be recovered and recycled by a simple filtration of the reaction mixture. It can be reused in further reactions with only minor decrease in activity. Additionally, we were able to produce a variety of enyne derivatives under modified conditions employing the same Pd-EnCat(TM) source. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheirn, Germany, 2009)