With the aim to easily recover and reuse the catalyst, an efficient amino alcohol catalyst previously tested in the asymmetric addition of diethylzinc to several aromatic aldehydes has been immobilized on proper functionalized superparamagnetic core–shell magnetite–silica nanoparticles and employed in the Henry reaction in the semi-homogeneous phase. The nanocatalyst exhibits a promising catalytic activity that remains unchanged in the three catalytic cycles performed. The results prove that highly efficient catalysts, by being immobilized on suitable magnetic nanosupports, can be easily recovered and reused, maintaining their catalytic behavior.

Hydroarylation reactions play a pivotal role in organic chemistry due to their versatility and efficiency. In the last 10 years, the scientific production around this reaction has been very high, but in its asymmetric version, the results are less. In this mini review, selected literature examples are considered to draw attention to directions of the asymmetric hydroarylation reaction mediated by transition metal catalysts. The selected works were grouped in two main sections. In the first, we reported examples relating the narrower definition of hydroarylation, namely the metal-catalyzed processes where inactivated aryl moiety undergoes a direct functionalization via insertion of an unsaturated compound. In the second part, hydroarylation reactions take place with the use of pre-activated aryl substrates, usually aryl-iodides or aryl-boronated.

Ochratoxin A (OTA) is a mycotoxin with a serious impact on human health. In Mediterranean countries, the black Aspergilli group, in particular Aspergillus carbonarius, causes the highest OTA contamination. Here we describe the synthesis of three polyphenolic flavonoids: 5-hydroxy-6,7-dimethoxy-flavone (MOS), 5,6-dihydroxy-7-methoxy-flavone (NEG), and 5,6 dihydroxy-flavone (DHF), as well as their effect on the prevention of OTA biosynthesis and lipoxygenase (LOX) activity in A. carbonarius cultured in a conducive liquid medium. The best control effect on OTA biosynthesis was achieved using NEG and DHF. In fungal cultures treated with these compounds at 5, 25, and 50 μg/mL, OTA biosynthesis significantly decreased throughout the 8-day experiment. NEG and DHF appear to have an inhibiting effect also on the activity of LOX, whereas MOS, which did not significantly inhibit OTA production, had no effect on LOX activity. The presence of free hydroxyls in catecholic position in the molecule appears to be a determining factor for significantly inhibiting OTA biosynthesis. However, the presence of a methoxy group in C-7 in NEG could slightly lower the molecule’s reactivity increasing OTA inhibition by this molecule at 5 μg/mL. Polyphenolic flavonoids present in edible plants may be easily synthesized and used to control OTA biosynthesis.

Asymmetric synthesis of warfarin in ESI-microdroplets by using chiral 1,2-diamino organocatalysts.