The role of water in lanthanide-catalyzed carbon-carbon bond formation.

Luminescence-decay measurements in combination with high-performance liquid chromatography analyses were used to study the relationship between rates of catalysis and water-coordination numbers of europium-based precatalysts in the aqueous Mukaiyama aldol reaction. A correlation between reactivity and water-coordination number was observed and is reported here.

A new class of ligands for aqueous, lanthanide-catalyzed, enantioselective Mukaiyama aldol reactions.

The development of aqueous methods for generating enantiopure ß-hydroxy carbonyl compounds is an important goal because these subunits compose many bioactive compounds and the ability to synthesize these groups in water has environmental and cost benefits. In this communication, we report a new class of ligands for aqueous, lanthanide-catalyzed, asymmetric Mukaiyama aldol reactions for the synthesis of chiral ß-hydroxy ketones. Furthermore, we have used luminescence-decay measurements to unveil mechanistic information regarding the catalytic reaction via changes in water-coordination number. The precatalysts presented here yielded ß-hydroxy carbonyls from aliphatic and aryl substrates with outstanding syn:anti ratios and enantiometric excesses of up to 49:1 and 97%, respectively.

Dynamic measurements of aqueous lanthanide triflate-catalyzed reactions using luminescence decay.

There is tremendous interest in water-compatible lanthanide triflate-based catalysts for carbon-carbon bond forming reactions; however, poor understanding of their aqueous mechanism severely limits the ability to increase the utility of these catalysts. Here, we report dynamic measurements of the water-coordination number of lanthanide triflate-based catalysts using luminescence-decay measurements in a range of aqueous systems. This unique characterization method is a reliable, convenient, and fast approach to analyze lanthanide-based catalysts in aqueous systems.