Palladium metal catalysts in Heck CC coupling reactions

This review is devoted to the application of palladium metal catalysts to the Heck reaction (arylation or vinylation of alkenes with aryl or vinyl halides and pseudohalides). The number of relevant articles published in recent years shows steadily increasing interest in this field. A brief outline of the historical development of heterogeneous catalysis as applied to the Heck reaction is given (Section 2). Both supported metal catalysts (Section 3) and stabilized colloidal palladium catalysts (Section 4) are included. Heterogeneous catalysts supported over different kinds of supports (carbon, inorganic oxides, molecular sieves, polymeric materials, etc.) are reviewed under separate headings. Particular attention is paid to the metal leaching and the nature of catalysis, two tightly connected problems which appear to be still controversial (Section 5). Some perspectives are shortly discussed in the final section (Section 6).