Studies directed toward total synthesis of rhodocomatulins: A regioselective synthesis of brominated hydroxyanthraquinones by anionic annulations

<p>In this work, brominated hydroxyanthraquinones, which are the core structural motif of naturally occurring bromorhodocomatulins, were successfully synthesized using Hauser annulation reaction as the key step. When brominated Michael acceptors (brominated <i>p</i>-quinone monoketals) and cyanophthalides or bromocyanophthalides (Hauser donors) were reacted under the annulation conditions, brominated anthraquinones were obtained with 81–87% yields for four examples. On acidic quenching, products were obtained as solid which were separated by filtration and purified by recrystallization in acetone. No chromatography was required.</p

Weakly Coordinating, Ketone-Directed Cp*Co(III)-Catalyzed C–H Allylation on Arenes and Indoles

Weakly coordinating, ketone-directed, regioselective monoallylation of arenes and indoles is reported using a stable and cost-effective high-valent cobalt­(III)-catalyst to access several important molecular building blocks. The allylation proceeds smoothly with a variety of substrates in the presence of various electron-rich and -deficient substituents. The method was applied to the formal synthesis of an ancisheynine alkaloid, a highly conjugated azatetracene, and isochroman. The mechanistic study reveals that the allylation reaction follows a base-assisted intermolecular electrophilic substitution pathway