High Activation of Carbonyl Groups with Bidentate Lewis Acid Catalysts.

Bidentate Lewis acid catalysts in asymmetric synthesis*

The chemistry of bidentate Lewis acids belongs to an unexplored field of science, and so far has been only poorly studied. This paper illustrates the design of several bidentate Al and Ti Lewis acids, and their successful application to selective organic synthesis, particularly to asymmetric synthesis. For example, a new, chiral bidentate Ti(IV) complex is successfully designed by adding commer...

Primary amine-metal Lewis acid bifunctional catalysts based on a simple bidentate ligand: direct asymmetric aldol reaction.

A novel class of primary amine-metal Lewis acid bifunctional catalysts based on a bidentate ligand was developed. These catalysts were highly efficient in catalyzing the direct asymmetric aldol reactions of ketones offering excellent stereoselectivity. The aldol reactions required a low catalyst loading (2.5 mol%), and were water compatible.

Lewis acid double metal cyanide catalysts for hydroamination of phenylacetylene.

Double metal cyanides (DMCs) are highly active recyclable heterogeneous catalysts for hydroamination of phenylacetylene with 4-isopropylaniline. The best hydroamination yields are obtained with Zn-Co DMCs, especially if the particle size is decreased by a reverse emulsion synthesis technique.

Electrophilic bis-fluorophosphonium dications: Lewis acid catalysts from diphosphines.

Stepwise oxidation of 1,8-bis(diphenylphosphino)naphthalene and a series of (oligo)methylene-linked diphosphines with XeF2 followed by fluoride abstraction yields a family of compounds featuring phosphine, phosphonium and phosphorane moieties in close proximity. The bisphosphonium ions [(C10H6)(Ph2PF)2]2+ (5) and [CH2(Ph2PF)2]2+ (9a) exhibit remarkable Lewis acidity arising from the proximity o...

Heteroatom-Substituted Delaminated Zeolites as Solid Lewis-Acid Catalysts