Copper-Catalyzed Conjugate Addition of Carbonyls as Carbanion Equivalent via Hydrazones

Copper-catalyzed conjugate addition is a classic method for forming new carbon-carbon bonds. However, copper has never showed catalytic activity for umpolung carbanions in hydrazone chemistry. Herein, we report a facile conjugate addition of hydrazone catalyzed by readily available copper complexes at room temperature. The employment of mesitylcopper(I) and electron-rich phosphine bidentate ligand is a key factor affecting reactivity. The reaction allows various aromatic hydrazones to react with diverse conjugated compounds to produce 1,4-adducts in yields of about 20 to 99%.

Alkene homologation via visible light promoted hydrophosphination using triphenylphosphonium triflate

A hydrophosphination reaction of alkenes with triphenylphosphonium triflate under photocatalytic conditions is described. The reaction is promoted by naphthalene-fused N-acylbenzimidazole and is believed to proceed through intermediate formation of a phosphinyl radical cation. The resulting phosphonium salts are directly involved in the Wittig reaction leading to homologated alkenes.

Hydrozirconation/bromination, followed by a Michaelis-Arbuzov reaction, as a convenient approach towards polyfunctional glycosylphosphonates

In this note, an hydrozirconation/bromination/Michaelis-Arbuzov sequence was developped to introduce a trimethylene phosphonate unit on ketopyranosides. Performed on polyfunctional substrates bearing orthogonal protecting groups, this new approach provided a straightforward entry towards a large diversity of glycophosphomimetics having a quaternary anomeric position.

β-Hydroxy- and β-Aminophosphonate Acyclonucleosides as Potent Inhibitors of Plasmodium falciparum Growth

Malaria is an infectious disease caused by a parasite of the genus Plasmodium, and the emergence of parasites resistant to all current antimalarial drugs highlights the urgency of having new classes of molecules. We developed an effective method for the synthesis of a series of β-modified acyclonucleoside phosphonate (ANP) derivatives, using commercially available and inexpensive materials (i.e., aspartic acid and purine heterocycles). Their biological evaluation in cell culture experiments and SAR revealed that the compounds' effectiveness depends on the presence of a hydroxyl group, the chain length (four carbons), and the nature of the nucleobase (guanine). The most active derivative inhibits the growth of Plasmodium falciparum in vitro in the nanomolar range (IC₅₀ = 74 nM) with high selectivity index (SI > 1350). This compound also showed remarkable in vivo activity in P. berghei-infected mice (ED₅₀ ∼ 0.5 mg/kg) when administered by the ip route and is, although less efficient, still active via the oral route. It is the first ANP derivative with such potent antimalarial activity and therefore has considerable potential for development as a new antimalarial drug.

UV-mediated hydrophosphinylation of unactivated alkenes with phosphinates under batch and flow conditions

A UV-mediated hydrophosphinylation of unactivated alkenes with H-phosphinates and hypophosphorous acid under radical free conditions is presented. The reaction affords selectively a large number of structurally diverse organophosphorous compounds in moderate to good yields under mild reaction conditions in the presence of an organic sensitizer as catalyst irradiated by UV-A LEDs. Furthermore, the high yielding hydrophosphinylation in continuous flow is disclosed.

Rapid synthesis of carbonucleoside phophonate analogues as potential antiviral agents via a hydrophosphonylation reaction of ethynyl carbocyclic precursors

Carbonucleoside phosphonate analogues were readily obtained using a free-radical hydrophosphonylation reaction under UV/Vis light irradiation of alkyne carbocyclic precursors.