Heck Alkynylation (Copper-Free Sonogashira Coupling) of Aryl and Heteroaryl Chlorides, Using Pd Complexes of t-Bu2(p-NMe2C6H4)P: Understanding the Structure-Activity Relationships and Copper Effects
Xiaotao Pu, Hongbo Li and Thomas J. Colacot*
*Johnson Matthey Catalysis and Chiral Technologies, 2001 Nolte Drive, West Deptford, New Jersey 08066, United States, Email: colactjjmusa.com
X. Pu, H. Li, T. J. Colacot, J. Org. Chem., 2013, 78, 568-581.
DOI: 10.1021/jo302195y (free Supporting Information)
t-Bu2(p-NMe2C6H4)P is an efficient ligand for palladium catalysts in Heck alkynylation of various aryl halides with a range of aryl- and alkyl-acetylenes in excellent yields, under relatively low Pd loadings. Preliminary mechanistic studies on the negative copper effect and substrate effect of aryl acetylenes help to better understand the cross-coupling pathway of Heck alkynylation.
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