Reusable heterogeneous bifunctional silica-supported Ag ₂ O/Im ⁺ Cl ⁻ catalyst in carboxylative cyclization reaction of propargyl alcohols by the efficient utilization of CO ₂ under ambient conditions.

A highly active hydrotalcite-supported Ag/Pd bimetallic nanocluster catalyst has been developed by a simple, easy and safe chemical reduction method. The catalyst was characterized by high-resolution transmission electron microscopy (HR-TEM), which revealed very small (3.2 ± 0.7 nm) nanoclusters with a narrow size distribution. The bimetallic Ag/Pd catalyst showed strong cooperation between Ag and Pd for the alcohol oxidation reaction. The developed catalyst provided an efficient and environmentally friendly method for alcohol oxidation and one-pot cross-aldol condensation in water. A broad scope of α,β-unsaturated ketones with good to excellent yields were obtained under very mild conditions. This catalytic system offers an easy preparation method with a simple recovery process, good activity and reusability of up to five cycles without significant loss in the catalytic activity.

Side-chain derivatives of eurotiumide A, a dihydroisochroman-type natural product, have been synthesized and their antimicrobial activities described. Sixteen derivatives were synthesized from a key intermediate of the total synthesis of eurotiumide A, and their antimicrobial activities against two Gram-positive bacteria, methicillin-susceptible and methicillin-resistant Staphylococcus aureus (MSSA and MRSA), and a Gram-negative bacterium, Porphyromonas gingivalis, were evaluated. The results showed that derivatives having an iodine atom on their aromatic ring instead of the prenyl moiety displayed better antimicrobial activity than eurotiumide A against MSSA and P. gingivalis. Moreover, we discovered that a derivative with an isopentyl side chain, which is a hydrogenated product of eurotiumide A, is the strongest antimicrobial agent against all three strains, including MRSA.