Margherita De Rosa

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.

Enantioselective aldol condensation of O-silyl dienolates to aldehydes mediated by chiral BINOL–titanium complexes

Abstract Chiral BINOL–titanium complexes have been shown to catalyze enantioselective aldol reactions between dioxinone derivatives and a set of aldehydes. The aldol adducts are isolated in good yields and high enantioselectivities. A range of substitution patterns on the O-silyl dienolate is possible: alkyl and benzyl substituents are tolerated. A simple reaction protocol is described and provides an efficient alternative to the well-known methods for conducting enantioselective Mukaiyama aldol reactions.

SOLVENT FREE REACTION UNDER MICROWAVE IRRADIATION : A NEW PROCEDURE FOR EU+3 : CATALYZED MICHAEL ADDITION OF 1,3-DICARBONYL COMPOUNDS

CC bond formation via Michael addition is achieved in high yields and short times by employing catalytic amounts of EuCl3 in dry media under microwave irradiation.

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.

First enantioselective synthesis of manoalide: application of aldehyde–dioxinone enantioselective condensation

Abstract Manoalide, an analgesic and anti-inflammatory sesterterpene, has been stereoselectively synthesized for the first time. The C-4 stereogenic centre has been introduced in an early step by enantioselective aldol condensation using a Ti(OiPr)4/(R)-(+)-binol complex.

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.

K10 montmorillonite catalysis. C-C Bond formation by catalyzed conjugate addition and alkoxyalkylation of 1,3-dicarbonyl compounds

The intrinsic catalytic properties of K10 and KSF montmorillonites allow the achievement of more environmentally acceptable procedures for C–C bond formation: Michael addition and α-alkoxyalkylation of 1,3-dicarbonyl compounds are performed by a convenient and cheap procedure based on the employment of montmorillonites as heterogeneous, reusable catalysts.

An easy approach to chiral non-racemic 6-(furan-3-yl)-5,6-dihydro-pyran-2-ones

Abstract Chiral non-racemic 6-(furan-3-yl)-pyran-2-one derivatives, key-intermediates in the preparation of compactin, manoalide and cacospongionolide subunits, are easily accessible through a rapid and convenient six-step sequence.

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.