Simona Bonollo

Sc(III)-Catalyzed Enantioselective Addition of Thiols to α,β-Unsaturated Ketones in Neutral Water

This report concerns Lewis acid catalyzed enantioselective sulfa-Michael addition in neutral water by using a very efficient Sc(OTf)(3)/bipyridine 1 catalytic system. It is noteworthy that the protocol presented employs water as a reaction medium and allows us to obtain very high stereoselectivity and satisfactory yields for β-keto sulphides deriving from aliphatic thiols. The recovery and reuse of both the aqueous medium and the catalytic system is also reported.

A green route to β-amino alcohols via the uncatalyzed aminolysis of 1,2-epoxides by alkyl- and arylamines

Under mildly basic and pH-controlled aqueous conditions the aminolysis of 1,2-epoxides 1a–g by alkyl- and arylamines 2a–k is generally highly regioselective giving the corresponding β-amino alcohols in satisfactory to excellent yields.

E-factor minimized protocols for the polystyryl-BEMP catalyzed conjugate additions of various nucleophiles to α,β-unsaturated carbonyl compounds

Efficient protocols for the addition of carbon-, sulphur- and nitrogen-nucleophiles to α,β-unsaturated carbonyl compounds catalyzed by PS-BEMP have been reported. The adoption of solvent-free conditions (SolFC) was crucial for improving the efficiency of all the processes, while by using an organic reaction medium poor results were obtained. Addition reactions were performed by using equimolar amounts of reagents, and the products were isolated by simple filtration with the minimal amount of organic solvent. This approach allowed the E-factor, a measure of the waste of a reaction, to be minimized. Further waste minimization (95.7% compared to batch protocol) has been accomplished by defining a larger scale continuous-flow protocol operating under SolFC.

A Protocol for Accessing the β-Azidation of α,β-Unsaturated Carboxylic Acids

This contribution reports the preparation and use of a new immobilized catalyst, PS-DABCOF (9), which has been specifically designed to access for the first time the efficient β-azidation of α,β-unsaturated carboxylic acids.

JandaJel as a polymeric support to improve the catalytic efficiency of immobilized-1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) under solvent-free conditions

JandaJel, with its greater spacing between the linear polymeric chains compared to that of polystyrene matrices, is a very efficient support for improving the catalytic efficiency of TBD under SolFC.

E-Factor minimized hydrophosphonylation of aldehydes catalyzed by polystyryl-BEMP under solvent-free conditions

An efficient protocol for the hydrophosphonylation of aromatic and aliphatic aldehydes catalyzed by PS-BEMP under solvent-free conditions (SolFC) has been reported. Addition reactions were performed by using equimolar amounts of reagents and the resulting α-hydroxyphosphonates were isolated with simple workup procedures. A large scale protocol for the preparation of a representative α-hydroxyphosphonate 3a has been also set up using a flow reactor.

Multistep Flow Procedure for the Waste-Minimized Preparation of N-Boc-ß-Amino Ketones

A clean and efficient protocol for the synthesis of a wide variety of N-Boc-β-amino ketones 3a-g has been defined using flow approach. The multistep procedure is based on the β-azidation of unsaturated ketones, consecutive reduction of the azido group, and concomitant amino group protection, and furnishes the desired products in good yields and very low E-factors ranging from 3.1 to 5.6. In batch conditions and by water as reaction medium, poorer yields and complicated reaction mixtures are obtained. Adoption of the flow approach, which combines transformations performed in solvent-free conditions and in EtOAc, has been essential in order to avoid side reactions, poisoning of the reduction catalyst, and use of minimal amount of reactants.

A new sustainable protocol for the synthesis of nitroaldol derivatives via Henry reaction under solvent-free conditions

A new protocol for the Henry addition of nitroalkanes to aryl- and alkyl-aldehydes promoted by PS-BEMP under solvent-free conditions (SolFC) is presented. The corresponding nitroaldol products were obtained in good yields and short times; furthermore minimization of the reaction waste was achieved by reducing the use of organic solvents. Extension of the protocol was obtained by setting up the tandem Michael-Henry reaction of α,β-unsaturated aldehydes and nitroalkane to yield the corresponding dinitro derivatives.

A catalytic approach to the metal-free reaction of epoxides with ketene silyl acetals for accessing γ-lactones.

The first catalytic approach to the nucleophilic addition of silyl ketene acetals 2 to epoxides 1 is reported. The defined protocol is metal-free using tetrabutylammonioum fluoride as the catalyst. It works in a very efficient manner under solvent-free conditions (SolFC) allowing γ-lactones 3 to be directly obtained with high regioselectivities and yields.