Efficient Multicomponent Synthesis of Diverse Antibacterial Embelin-Privileged Structure Conjugates.

A library of embelin derivatives has been synthesized through a multicomponent reaction from embelin (), aldehydes and privileged structures such as 4-hydroxycoumarin, 4-hydroxy-2-pyran-2-one and 2-naphthol, in the presence of InCl as catalyst. This multicomponent reaction implies Knoevenagel condensation, Michael addition, intramolecular cyclization and dehydration. Many of the synthesized compounds were active and selective against Gram-positive bacteria, including one important multiresistant clinical isolate.

Domino Synthesis of Embelin Derivatives with Antibacterial Activity.

A series of dihydropyran embelin derivatives was synthesized through a direct and highly efficient approach based on a domino Knoevenagel intramolecular hetero-Diels-Alder reaction from natural embelin (1), using unsaturated aldehydes in the presence of organocatalysts such as ethylendiamine diacetate or l-proline. The aliphatic aldehydes yielded exclusively trans adducts, while mixtures of trans and cis isomers were found in reactions with aromatic aldehydes, with the cis form always predominating. Some of the compounds obtained were active and selective against Gram-positive bacteria, including multiresistant Staphylococcus aureus clinical isolates.

Multicomponent synthesis of antibacterial dihydropyridin and dihydropyran embelin derivatives.

A series of dihydropyran and dihydropyridin embelin derivatives were synthesized through a novel and straightforward one-pot protocol based on a three-component reaction with embelin, aldehydes, and cyclic enaminones as synthetic imputs. The type of substituent on the nitrogen atom of the β-enaminone is key to obtain nitrogenated or oxygenated rings. The obtained compounds were active against Gram-positive bacteria, including multiresistant Staphylococcus aureus clinical isolates.