Regio- and enantioselective intermolecular hydroacylation: substrate-directed addition of salicylaldehydes to homoallylic sulfides.

We report a Rh-catalyzed, regio- and enantioselective intermolecular olefin hydroacylation under mild conditions. Hydroacylations between homoallylic sulfides, containing a substrate-bound directing group, and salicylaldehyde derivatives occur in the presence of a spiro-phosphoramidite ligand, (R)-SIPHOS-PE, to give α-branched ketones in >20:1 selectivity and up to 97% ee. Our conditions are also applicable to the asymmetric intermolecular hydroacylation of 1,2-disubstituted olefins.

Rh-catalyzed intramolecular olefin hydroacylation: enantioselective synthesis of seven- and eight-membered heterocycles.

This communication describes the first rhodium-catalyzed intramolecular olefin hydroacylation to produce medium-sized heterocyclic ketones with high regio- and enantiocontrol. Both alpha- and beta-substituted ketones can be produced, depending on catalyst choice and substrate structure. In this stereoselective C-H bond functionalization, ethers, sulfides, and sulfoxides function as effective directing groups. Results from an isotopic labeling study suggest reductive elimination is not the turnover-limiting step in this olefin hydroacylation; thus, the proposed mechanism is distinct from those previously reported.

Combinatorial polyelectrolyte multilayer film fabrication.

A combinatorial strategy for the fabrication of a library of polyelectrolyte multilayer films is presented in this paper. This innovative approach involves the parallel formation of polyelectrolyte multilayer films in the individual wells of polystyrene microtitre plates under various deposition conditions. The progress of film formation was monitored via the intensity of the UV-vis absorbance of one of the depositing polyelectrolytes using a conventional microplate reader. We demonstrate the utility of this technique by building a library of 120 distinct polyelectrolyte multilayer films. Both the primer layer composition and salt content of the polyeletrolyte solutions were systematically varied in the preparation of films of nine bilayers. Film growth did not follow a linear adsorption regime for the first three bilayers regardless of the composition of the primer layer. We observed that increasing the sodium chloride concentration in the polyelectrolyte solutions resulted in increased polyelectrolyte absorption for all the conditions studied. The approach presented here is a convenient method of producing and characterizing multiple films rapidly and reproducibly, making it a valuable tool for optimizing film fabrication.

Catalytic hydroacylation as an approach to homoaldol products.

A method has been developed for the intermolecular hydroacylation of homoallyl alcohols with salicylaldehydes to furnish homoaldol products in 50-98% yields. The method also applies to the hydroacylation of 2-hydroxystyrenes. This work highlights the use of hydroacylation as a unified approach to both aldol and homoaldol products.