Laura Palombi

Synthesis of chiral oxazolidin-2-ones by 1,2-amino alcohols, carbon dioxide and electrogenerated acetonitrile anion

An improved electrochemical synthesis of chiral oxazolidin-2-ones from chiral 1,2-amino alcohols is obtained by direct electrolysis of solutions of MeCN–TEAP containing the amino alcohol, with subsequent CO2 bubbling and addition of TsCl. This synthesis avoids any addition of bases or probases and yields oxazolidinones in high yields.

Microwave-assisted oxidation of saturated and unsaturated alcohols with t-butyl hydroperoxide and zeolites

Abstract Under microwave irradiation 3A molecular sieves promote the oxidation of secondary (linear and cyclic) and benzylic alcohols to the corresponding carbonyl compounds by t-butyl hydroperoxide. Under the same conditions, α,β-unsaturated alcohols are converted into α,β-epoxyalcohols in regio- and diastereoselective way. Both oxidative processes can be performed under solvent-free conditions; however, epoxidation of allylic alcohols is found to proceed with more satisfactory efficiency in saturated aliphatic hydrocarbon (n-hexane or cyclohexane).

Bifunctional phase-transfer catalysis in the asymmetric synthesis of biologically active isoindolinones

Summary New bifunctional chiral ammonium salts were investigated in an asymmetric cascade synthesis of a key building block for a variety of biologically relevant isoindolinones. With this chiral compound in hand, the development of further transformations allowed for the synthesis of diverse derivatives of high pharmaceutical value, such as the Belliotti (S)-PD172938 and arylated analogues with hypnotic sedative activity, obtained in good overall total yield (50%) and high enantiomeric purity (95% ee). The synthetic routes developed herein are particularly convenient in comparison with the current methods available in literature and are particularly promising for large scale applications.

The first organocatalytic asymmetric synthesis of 3-substituted isoindolinones

Herein we describe the first asymmetric organocatalytic synthesis of 3-substituted isoindolinones in a convenient aldol-cyclization-rearrangement tandem reaction of malonates with 2-cyanobenzaldehyde. Bifunctional thiourea-cinchona catalysts proved to be particularly effective, giving the title compounds in high yields and moderate to good enantiomeric excesses. Moreover an efficient process of reverse crystallization led to a further enrichment up to >99% ee.

Organocatalysts and sequential asymmetric cascade reactions in the synthesis of functionalized isoindolinones and benzoindolizidinones

In this article we have disclosed a combination of versatile methodologies for the asymmetric synthesis and manipulation of isoindolinones and fused benzo-indolizidinones. On one hand, two consecutive asymmetric cascade reactions allow the synthesis of isoindolinones and fused benzo-indolizidinones, with the stereoselective construction of up to three stereocenters. On the other hand the study of the heterochiral crystallization and the easy functionalization of the obtained molecular platforms render the chemistry of these heterocyclic compounds particularly useful.

Diastereoselective epoxidation of allylic alcohols by t-butyl hydroperoxide/zeolites system

Abstract Commercial zeolites promotes the epoxidation of unsaturated alcohols in chemo- and diastereoselective way.

Cascade reactions of glycine Schiff bases and chiral phase transfer catalysts in the synthesis of α-amino acids 3-substituted phthalides or isoindolinones

The tuning of aldol/cyclization cascade reactions of glycine Schiff bases with 2-cyano benzaldehydes provides access to non-natural α-amino acid derivatives substituted alternatively with phthalides or isoindolinones, depending on the strength of the used base. Moreover, a preliminary screening of catalysts and conditions for development of asymmetric versions identified chiral bifunctional phase transfer catalysts as particularly promising, leading to the α-amino esters 3-substituted phthalides in high yields and good diastereo- and enantioselectivity.

Electrochemically induced Knoevenagel condensation in solvent- and supporting electrolyte-free conditions

Solvent- and supporting electrolyte-free electrochemically induced Knoevenagel condensation of malononitrile with aldehydes or ketones, at 40 °C, yields ylidenemalononitriles in high yields.

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.

Electrochemically-initiated Michael addition of chiral acetoacetic derivatives to methyl vinyl ketone: stereocontrolled construction of quaternary carbon centers

Abstract Stereoselective conjugate addition of chiral β-dicarbonyl derivatives to methyl vinyl ketone was promoted by electrolysis, using a catalytic amount of electricity. With respect to the metal-catalyzed methods, the electrochemical, metal-free conditions resulted in enhanced reactivity of the electrogenerated enolates, so that the Michael addition was found to occur under mild conditions and short reaction times, affording products with significant diastereoisomeric excesses. When Oppolzers sultam was used as the chiral inductor and prolonged reaction times were employed, a reversal in the stereoselectivity was observed, evidencing kinetic control in the electrochemically-induced addition and subsequent thermodynamic equilibration. The electrochemically-based method was also exploited for the elaboration of quaternary stereogenic carbon centers.