Reaction of carbohydrates with Vilsmeier reagent: a tandem selective chloro O-formylation of sugars

A convenient and efficient method for selective replacement of the primary hydroxyl groups of sugars by chlorine with concomitant O-formylation, compatible with the presence of a variety of functional groups, has been developed using the Vilsmeier–Haack reaction. Sugars having free primary hydroxyl groups mostly afforded the chloro-O-formylated product while sugars devoid of primary hydroxyl groups yielded only O-formylated products

Bioactive Sesterterpenoids from a Korean Sponge <i>Monanchora</i> sp.

Chemical investigation of a Korean marine sponge, <i>Monanchora</i> sp., yielded nine new sesterterpenoids (<b>1</b>–<b>9</b>) along with phorbaketals A–C (<b>10</b>–<b>12</b>). The planar structures were established on the basis of NMR and MS analysis, and the absolute configurations of <b>1</b>–<b>9</b> were defined using the modified Mosher’s method and CD spectroscopic data analysis. Compounds <b>1</b>–<b>8</b>, designated as phorbaketals D–K, possess a spiroketal-modified benzopyran moiety such as phorbaketal A, and their structural variations are due to oxidation and/or reduction of the tricyclic core or the side chain. Compound <b>9</b>, designated as phorbin A, has a monocyclic structure and is proposed to be a possible biogenetic precursor of the phorbaketals. Compounds <b>1</b>–<b>9</b> were evaluated for cytotoxicity against four human cancer cell lines (A498, ACHN, MIA-paca, and PANC-1), and a few of them were found to exhibit cytotoxic activity