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.
The organocatalyzed addition of several malonates to 1,4-benzoquinones affords benzofuranones bearing a quaternary stereocenter with good enantioselectivity. This reaction is an intramolecular desymmetrization since it proceeds through the formation of an arylated achiral malonate that cyclizes to give the reaction product. The addition rate of the quinone dramatically affects the reaction yield which was originally low.
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