Site-selective Suzuki-Miyaura reactions of the bis(triflate) of 1,3-dihydroxyanthraquinone

Cytotoxic quinones from the aerial parts of Morinda umbellata L

Although Morinda umbellata L. has been used in numerous folk medicines, there is a lack of phytochemical studies on this plant. Sixteen undescribed quinones, namely, ten anthraquinones (umbellatas A-J), one naphthohydroquinone (umbellata K), one naphthohydroquinone dimer (umbellata L), and four dinaphthofuran quinones (umbellatas M-P), were isolated from the aerial parts of Morinda umbellata L. (Rubiaceae). The structures of all the isolated quinones were elucidated based on spectroscopic methods. Four of the unknown quinones (umbellatas A, H, K and M) showed potent cytotoxic effects against A431, A2780, NCI-H460, HCT116, HepG2, and MCF-7 human cancer cell lines with IC₅₀ values of 1.3-7.1 μM. These results reveal potential lead compounds for the development of new anticancer agents.

Synthesis of functionalized para- and meta-terphenyls based on site-selective Suzuki cross-coupling reactions of bis(triflates) of methyl 2,5-dihydroxybenzoate and methyl 2,4-dihydroxybenzoate

The palladium(0)-catalyzed Suzuki cross-coupling reaction of the bis(triflates) of methyl 2,5-dihydroxybenzoate and methyl 2,4-dihydroxybenzoate afforded para- and meta-terphenyls, respectively. The reactions proceeded with very good site selectivity in favor of the sterically less hindered carbon atom.