Catalytic hydration of neutral isonitriles to yield the corresponding N-formylamides was achieved by reversible encapsulation in a self-assembled hexameric resorcin[4]arene capsule. Encapsulation of a photochromic dithienylethene bis-cation provides different levels of competitive inhibition depending on the geometry assumed by the cationic inhibitor.
Reversible encapsulation of [Ru(bpy)(3)](2+) within a self-assembled hexameric resorcin[4]arene capsule turns off the photocatalytic aerobic oxidation of an aliphatic sulfide. Upon addition of a competitive cationic guest, the Ru(II) catalyst is released into solution where its catalytic activity is restored.
The enantioselective Baeyer-Villiger oxidation of cyclic ketones is a challenging reaction, especially when using environmentally friendly oxidants. The reaction was carried out in water by using soft Lewis acid Pt(II) complexes that have chiral diphosphines as well as monophosphines. Addition of a surfactant is crucial, which leads to the formation of micelles that act as nanoreactors in which the substrate and catalyst encounter each other in an ordered medium that in several cases positively influences both the conversion and the selectivity of the reactions. This is due to the combination of the hydrophobic effect (which confines the components of the reaction in the micelles), together with supramolecular interactions between the partners within the ordered palisade provided by the alkyl chains of the surfactant. For the oxidation of meso-cyclobutanones, addition of surfactant allowed the reaction to proceed in high yields and the enantiometic excess (ee; 56%) was higher than in organic solvents. Subsequent extension to meso-cyclohexanones resulted in a general decrease in yields but an enhancement of enantioselectivity (ee up to 92%) moving from organic to water-surfactant media, regardless of the substrate or the catalyst employed. Different behaviour was observed with chiral cyclobutanones 7 and 10: with 7 the best catalyst was 1 g, whereas with the larger substrate, 10, complexes 1 a-b performed better in terms of enantioselectivity. Each combination of substrate, catalyst and surfactant is a new system and supramolecular reciprocal interactions together with the hydrophobic character of the counterparts play crucial roles. The asymmetric Baeyer-Villiger oxidation in water catalyzed by 1 a-h in the presence of micelles is a viable reaction that often benefits from the hydrophobic effect, leading to substantial increases in enantioselectivity.
A micellar environment enables catalytic, diastereoselective and enantioselective Baeyer-Villiger oxidation of cyclobutanones (ee up to 90%) with H 2 O 2 as oxidant using Co(Salen) catalyst 1, while the same catalytic system is inactive in organic solvents.This journal is
Incorporation of the dithienylethene moiety as a substituent provides new 'switchable' phosphine ligands whose electronic properties are reversibly modulated by light. The presence of electron-withdrawing substituents in the photochromic unit increases the s-donation gap between the photo-modulated open and closed phosphine isomers.
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