Rosaria Villano

An efficient asymmetric aldol reaction of Chan's diene promoted by chiral Ti(IV)–BINOL complex

Abstract 1,3-Bis-(trimethylsilyloxy)-1-methoxy-buta-1,3-diene (Chans diene) can be conveniently used in asymmetric aldol reaction with aromatic, heteroaromatic, α,β-unsaturated and aliphatic aldehydes in the presence of catalytic amounts (2–8% mol) of chiral Ti(IV)/( R )-BINOL complex.

Enantioselective aldol condensation of 1,3-bis-(trimethylsilyloxy)-1-methoxy-buta-1,3-diene promoted by chiral Ti(IV)/BINOL complex

Abstract Enantiomerically enriched δ-hydroxy-β-ketoesters are easily available by aldol condensation of 1,3-bis-(trimethylsilyloxy)-1-methoxy-buta-1,3-diene in the presence of Ti(O-iPr)4/(S)-(−)-BINOL system. All reaction mixtures were separated by column chromatography and mostly isolated in moderate to good yields and all in high enantiomeric excesses.

A convenient catalytic procedure for the highly enantioselective aldol condensation of O-silyldienolates

Abstract In the presence of catalytic amount of chiral Ti(OiPr)4/BINOL (0.08 equiv.) the asymmetric aldol condensation of 6-methyl-4H-[1,3]-dioxin-4-one-derived silyloxydienes takes place in high yields and enantiomeric excesses with aromatic, heteroaromatic, unsaturated and aliphatic aldehydes. Notable amplification of enantiomeric excesses have been obtained by using enantioenriched catalytic systems.

Nonlinear effects and auto-induction in the asymmetric aldol condensation of synthetic equivalents of acetoacetic esters

Positive nonlinear effects, (+)-NLEs, have been detected in the Ti(IV)/BINOL complex-mediated catalytic asymmetric aldol reaction of three different masked acetoacetate esters. The use of a different procedure for the catalyst preparation disclosed the occurrence of aldol condensation of Chans diene through an auto-inductive process.

Asymmetric Friedel-Crafts Alkylation of Indole with Chalcones Catalyzed by Chiral Phosphoric Acids

The reaction of indole with chalcones, to give Michael-type adducts, was found to occur with good efficiency (up to 98% yield) and moderate enantioselectivity (up to 52% e.e.) in the presence of a chiral BINOL-based phosphoric acid. Furthermore, the alkylation products can be obtained in much higher e.e.s after one only crystallization.

Ti(IV)/BINOL-catalyzed asymmetric aldol reaction of a masked acetoacetic ester: pronounced influence of catalyst concentration on nonlinear effects

Initial concentration of enantioenriched or enantiopure catalysts proved to be an important factor for the achievement of a more pronounced amplification of ees in the Ti(IV)/BINOL-catalyzed aldol reaction of an O-silyldienolate.

Mo(CO)6-Catalyzed oxidation of furan derivatives to E- and Z-enediones by cumyl hydroperoxide

Abstract E- and Z-Enediones are easily accessible by controlled oxidation of 2,5-disubstituted furans with Mo(CO)6/cumyl hydroperoxide system. The use of t-butyl hydroperoxide, as oxygen donor, leads to the formation of 2H-pyran-3(6H)-one derivatives.

Mukaiyama-Michael vinylogous additions to nitroalkenes under solvent-free conditions

The first Mukaiyama-Michael vinylogous reaction of a dioxinone-derived silyl ether to nitroalkenes is reported. The conjugate addition is performed in absence of any catalyst under solvent-free conditions, proceeding with satisfactory efficiency with variously substituted nitroalkenes.Moreover, the first organocatalyzed Mukaiyama-Michael vinylogous reaction of trimethylsilyloxyfuran to nitroalkenes is described.The reaction is promoted by Brønsted acids under solvent-free conditions, taking place in moderate to good yield with variously substituted nitroalkenes..

1-Naphthyl-TADDOL/Emim BF4: A new catalytic system for the asymmetric addition of Chan’s diene to aromatic aldehydes

A new organocatalytic system was tested as a promoter for the asymmetric addition of Chan’s diene to aldehydes under solvent-free conditions. This new organocatalyst generated in situ by mixing 1-naphthyl-TADDOL derivative and Emim BF4 was able to give enantioenriched vinylogous aldols and hetero-Diels-Alder cycloadducts. A mechanistic investigation through the detection of nonlinear effects confirmed the involvement of the ionic liquid in the formation of a new catalytic supramolecular species.

Neutral lewis bases as activators of molecular sieves in the conjugate addition of 1,3-dicarbonyl compounds

The catalytic properties of 3 A molecular sieves in the promotion of Michael addition of 1,3-dicarbonyl compounds are significantly improved by activation with several neutral Lewis bases. Comparable efficiency can be observed under solvent-free conditions.