Selective oxidation of 8,8'-hydroxylated binaphthols to bis-spironaphthalenones or binaphtho-para- and binaphtho-ortho-quinones

Nickel-Catalyzed Ring-Opening C-O Functionalization of peri-Xanthenoxanthenes for 8-Substituted Binaphthol Synthesis

Herein, we disclose the Ni-catalyzed ring-opening C-O functionalization of peri-xanthenoxanthenes using Grignard reagents that forms 8-monofunctionalized binaphthols. 1,2-Bis(dicyclohexylphosphino)ethane was the best ligand for alkylations and ICy for arylation. After mechanistic investigations, we assumed that the reaction proceeds via C-O reduction and subsequent C-O functionalization. To verify the mechanism, the intermediate after reduction was isolated. Moreover, the asymmetric addition, using 8-octylbinaphthol after optical resolution, was studied.

Total Synthesis of Tetarimycin A, (±)-Naphthacemycin A9, and (±)-Fasamycin A: Structure-Activity Relationship Studies against Drug-Resistant Bacteria

Making use of a reductive olefin coupling reaction and Michael-Dieckmann condensation as two key operations, we have completed a concise total synthesis of tetarimycin A, (±)-naphthacemycin A₉, and (±)-fasamycin A in a highly convergent and practical protocol. Synthetic procedures thus developed have also been applied to provide related analogues for structure-activity relationship studies, thereby coming to the conclusion that the free hydroxyl group at C-10 is essential for exerting inhibitory activities against a panel of Gram-positive bacteria, including drug-resistant strains VRE and MRSA.

Alkynylation/dearomatizative cyclization to construct spiro[5.5]undecanes

A one-pot process to construct spiro[5.5]undecanes.

Axial chiral bisbenzophenazines: solid-state self-assembly via halide hydrogen bonds triggered by linear alkanes

An axial chiral tetrachlorinated bisbenzo[a]phenazine has been discovered that undergoes an alkane-induced shift in the solid state from a disordered amorphous form to an ordered polycrystalline form. This phase transition is caused by the formation of pores that accommodate linear alkanes of varying lengths with a very strong affinity as judged by differential scanning calorimetry. Single crystal X-ray structure analysis revealed that a series of weak phenolic OH···Cl hydrogen bonds dictates the pore structure. These weak interactions can be disrupted mechanically, causing the material to revert to the amorphous form. Notably, the interchange between the amorphous and crystalline forms is readily reversible and is easily observed by characteristic colorimetric changes. Measurements via photoimage processing reveal that the degree of color change is dictated by the type of alkane employed.

Divergent approach to the bisanthraquinone natural products: total synthesis of (S)-bisoranjidiol and derivatives from binaphtho-para-quinones

The development of the first asymmetric synthesis of a chiral anthraquinone dimer is outlined, resulting in the first total synthesis of (S)-bisoranjidiol. Rather than a biomimetic dimerization retrosynthetic disconnection, the anthracenyl ring systems are generated after formation of the axially chiral binaphthalene framework. This synthetic strategy has enabled the synthesis of several analogues. Key features of the synthesis include the enantioselective coupling of a hindered 2-naphthol containing substitution peri to the site of C-C bond formation, the regioselective oxidation of 8,8'-hydroxylated binaphthols to binaphtho-para-quinones, and a tandem regioselective Diels-Alder/aromatization reaction.