Ricerc@Sapienza

The Henry reaction, also named nitroaldolic, is one of the most important ways to form a C-C bond and it is promising due to its economy and high versatility of the nitro group,[1] which can be transformed in several functional groups through the Nef reaction.[2]

In recent years it is growing the interest in magnetic nanoparticles as supports for chiral ligands, in order to develop a nanostructured catalytic system which combines advantages of homogeneous and heterogeneous catalysis, that is, simple recovery and high catalytic efficiency [1]. In a previous work our research group has developed the highly efficient ligand L1 in the addition of diethylzinc to aromatic aldehydes [2] (Scheme 1), but our ultimate aim was to achieve an analogous of L1 that could be immobilized on magnetic nanoparticles in order to develop a magnetic recoverable

Heterogeneous phase catalysis has attracted scientific community in the last few decades because, supporting chiral catalysts on solid supports, it is possible to easily recover and reuse them for several catalytic cycles. Especially the use of magnetic nanoparticles is highly advantageous, both for their high dispersibility in organic solvents that the simple and non-expensive recovery by magnetic decantation. Our attention has been focused on the modification of known efficient chiral ligands’ structure, in order to let them be anchorable on Fe3O4@SiO2 nanoparticles.

BACKGROUND: Three protocols are presented in order to immobilise a laccase (EC 1.10.3.2) from Trametes versicolor on chitosan. In particular, chitosan is functionalized with glutaraldehyde and epichlorohydrin to explore to what extent the conjugation of the enzyme is affected by a carbonyl- or epoxy-modified surface, respectively. In addition, an oxidation procedure is tested to modify, for the first time, the carbohydrate moiety of the enzyme and exploit it for linking with the amine group of chitosan.