Combination of enzymes and metal catalysts. A powerful approach in asymmetric catalysis.

Palladium catalysed allylic substitution has emerged as one of the more useful synthetic methods for the construction of C-C and C-X bonds. The reaction offers the advantages of mild reaction conditions, as well as the ability to accomodate a wide range of nucleophiles and their electrophilic partners. The issues of regiocontrol, diastereocontrol and enantiocontrol have been documented by a number of researchers over the last twenty years. The levels of selectivity in many cases are very high, and current research is driving these selectivities higher still. A greater understanding of the nature of the process is occurring as more detailed mechanistic and structural studies are being undertaken. Many uses have been found for palladium catalysed allylic substitution methodology, since the strong stereocontrol allows for the selective formation of numerous products. A few other metals are also able to catalyse allylic substitution, with modified stereochemical behaviour, although these are currently less well documented than for palladium catalysed process.

Selectivity in palladium catalysed allylic substitution

Contribution of Electrochemistry to Organometallic Catalysis

Palladium (Pd) complexes catalyzed many different types of organic reactions because the metal is able to coordinate many different organic substrates and is effective in almost all fundamental organometallic reactions such as oxidative addition, reductive elimination, nucleophilic addition, insertion reactions, and beta-elimination. The effectiveness of Pd's catalytic power to promote the formation of 1,2-and 1,4-alkenes and dienes from 1,3-dienes ad other alkenes is discussed. Nucleophilic attack on (Pi-olefins)-, (Pi-alkyl)- and (o-alkyl) palladium complexes and oxidation cleavage are of importance in these reactions.

Samuel M. McElvain

Papers

Isoerization of allylic acetates catalyzed by palladium. New method for stereocontrol.