Alkenes carboxylate/amino acid ligands

During the coverage period of this chapter, reviews have appeared on the following topics reactions of electrophiles with polyfluorinated alkenes, the mechanisms of intramolecular hydroacylation and hydrosilylation, Prins reaction (reviewed and redefined), synthesis of esters of /3-amino acids by Michael addition of amines and metal amides to esters of a,/3-unsaturated carboxylic acids," the 1,4-addition of benzotriazole-stabilized carbanions to Michael acceptors, control of asymmetry in Michael additions via the use of nucleophiles bearing chiral centres, a-unsaturated systems with the chirality at the y-position, and the presence of chiral ligands or other chiral mediators, syntheses of carbo- and hetero-cyclic compounds via Michael addition of enolates and activated phenols, respectively, to o ,jS-unsaturated nitriles, and transition metal catalysis of the Michael addition of 1,3-dicarbonyl compounds. ... 

Charette et al. examined a Rh(ll)-carboxylate catalyst with four amino acid derived M-phthaloyl ligands [129]. This catalyst has seen widespread use, for example in the cyclopropanation of alkenes with diazo compounds. Depending on the orientation of these ligands (up or down), four different symmetries are possible. Previous studies were unable to clarify which is the enantioselectively active one (Scheme 15). 

Trisubstituted acrylic acids, such as alkene (2.52), where the carboxylic acid is believed to bind to the amino groups of the ligand (2.54), also undergo enantioselective rhodium-catalysed hydrogenation. a-Methyldimamic acid is reduced with 99% ee using the rhodium catalyst prepared from a 2 1 mixture of PipPhos (2.16c) andtriphenylphosphine. ... 

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