Direct Observation of Palladium Leaching from Pd/C by a Simple Method: X-ray Absorption Spectroscopy of Heterogeneous Mixtures.

Herein, we show the detailed behavior of palladium leaching from palladium on charcoal by aqueous HCl, directly observed by X-ray absorption spectroscopy measurement employing a simplified reaction setup. While Pd is not affected by the addition of HCl, palladium oxide in nanoparticles readily reacts with HCl to form the ionic species [PdCl], even though these ions mostly remain adsorbed on the surface of activated charcoal and can only be detected at a low level in the solution phase. This finding provides a new aspect for control of the leaching behavior and robust usage of palladium on charcoal in organic reactions.

Lithium Binaphtholate-Catalyzed Michael Reaction of Malonates with Maleates and Its Application to the Enantioselective Synthesis of Tricarboxylic Acid Derivatives.

The Michael reaction of malonates with maleates afforded the corresponding adducts in high yields with high enantioselectivities (up to 98% enantiomeric excess (ee)) by using dilithium 3,3'-dichlorobinaphtholate as a catalyst. The obtained Michael adducts could be converted to optically active tricarboxylic acid (TCA) derivatives via the Krapcho reaction.

Enantioselective aldol reaction of trimethoxysilyl enol ether catalyzed by lithium binaphtholate.

[reaction: see text] An aldol reaction of trimethoxysilyl enol ether catalyzed by lithium binaphtholate, in which water serves as an additive and plays a pivotal role in stereoselectivities, was developed. This is the first example of an aldol reaction of trimethoxysilyl enol ether catalyzed by a chiral base.