Giovanni Poli

Limonene and other 1,1-dialkylsubstituted alkenes undergo a regioselective Pd(II)-catalyzed C–H/C–X coupling with (E) and (Z)-3-bromoacrylates affording 4,4-disubstituted sorbate derivatives as mixtures of geometrical isomers (16 examples). This coupling, unknown to date for the synthesis of 1,3-dienes, follows a mechanism distinct from the well-known Mizoroki–Heck, and works where the Mizoroki–Heck fails. Density functional theory (DFT) computations allowed to propose a plausible mechanism for this transformation.

Among the synthetic routes to isoxazole derivatives, since the 1960s, [3+2] cycloadditions of nitrile oxides have played a leading role, despite the need to prepare and use toxic and environmentally hazardous intermediates. The work reported here improves the sustainability of the process through the development of a three-component domino protocol involving the in situ formation of oximes, combined with the advantages inherent in the use of electricity. The electrochemical step occurs with cheap electrodes, avoids hazardous additives or electrolytes, and benefits from the use of equimolar amounts of aldehyde and alkene (or alkyne), as well as the possibility of recycling the solvent (acetonitrile/H2O 3:1) with improvements in atom economy and E-factor parameters with respect to previous approaches. Interestingly, the desired oximes could be efficiently generated by simply reacting the aldehyde and hydroxylamine hydrochloride in the presence of water.

Lignin‐based aryl 3‐hydroxypropanones were converted into indanones via a domino dehydration/Nazarov cyclization in the presence of a superacid. The cyclization was studied in detail, and the resulting indanones were engaged in two postfunctionalizations: a reduction/elimination domino sequence and a ring expansion. Lastly, the method has been successfully applied to the synthesis of the anti‐Alzheimer drug donepezil.

A versatile electrochemical method for the intramolecular aminobromination of alkenes has been developed. The method provides access to five‐, six‐, and seven‐membered heterocycles by exploiting tetrabutylammonium bromide as an electrolyte and bromine source. The mild electrochemical generation of Br ₂ plausibly allows the formation of a cyclic bromonium intermediate, as supported by density functional theory calculations.

Sustainable synthesis of novel lignin-derived, UV-degradable polymers that offer degradable bio-sourced alternatives to commodity plastics, such as polystyrene, has been reported.

Lignin-based aryl 3-hydroxypropanones were converted into indanones via domino dehydration/Nazarov cyclization in the presence of a superacid. The cyclization was studied in detail, and the resulting indanones were engaged in two postfunctionalizations: a reduction/elimination domino sequence and a ring expansion. Lastly, the method has been successfully applied to the synthesis of the anti-Alzheimer drug donepezil.

(Text in French) Pallado-catalyzed dehydrogenant: a terpene valorization mode.

Two new 2D coordination polymers were synthesized, scaled-up and applied as efficient and recyclable heterogeneous catalysts for the mild oxidation of α-pinene into value added products.

The coupling between bis(2-oxazolines) and two equivalents of aromatic aldehydes in the presence of catalytic amounts of NiCl₂ affords an ester-imine product in synthetically useful yields. This virtually unknown, 100% atom-economic transformation involves the formal metathesis between the C=N double bond of the bis(2-oxazoline) moiety, which undergoes ring-opening, and the C=O double bond of the aldehyde. The scope of this transformation is studied, and a mechanism is proposed based on DFT calculations.

Limonene undergoes a regioselective Pd(II)-catalyzed C(sp²)-H/C(sp²)-H coupling with acrylic acid esters and amides, α,β-unsaturated ketones, styrenes, and allyl acetate, affording novel 1,3-dienes. DFT computations gave results in accord with the experimental results and allowed for the formulation of a plausible mechanism. The postfunctionalization of one of the coupled products was achieved via a large-scale Sonogashira reaction conducted under micellar catalysis.