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.

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

The selective oxidation of a series of functionalized 8,8'-hydroxylated binaphthols to binaphtho-para- and binaphtho-ortho-quinones has been realized using either a Co-salen catalyst or ortho-iodoxybenzoic acid. A unique spirocyclic bis-spironaphthalenone was also obtained in good yield via a phenyliodonium diacetate promoted oxidative dearomatization.

Structural reassignment of a marine metabolite from a binaphthalenetetrol to a tetrabrominated diphenyl ether.

The structure of a reported natural product isolate has been revised from (S)-2,2'-dimethoxy-[1,1'-binaphthalene]-5,5',6,6'-tetraol to a known tetrabrominated diphenyl ether. After total synthesis of the reported binaphthalenetetrol was accomplished via a key reduction of a binaphtho-ortho-quinone, comparison of the physical properties and NMR spectroscopic data of the synthetic material indicated that the structure of the natural product isolate was incorrect. Evaluation of the authentic natural product suggested the structure is a tetrabrominated diphenyl ether, likely 3,5-dibromo-2-(3,5-dibromo-2-methoxyphenoxy)phenol.

Enantioselective total synthesis of (S)-bisoranjidiol, an axially chiral bisanthraquinone.

The first enantioselective total synthesis of the bisanthraquinone (S)-bisoranjidiol and an unnatural regioisomer has been accomplished. Key features of the synthesis include the asymmetric oxidative biaryl coupling of a hindered 8-substituted 2-naphthol, selective para-quinone formation, and regioselective tandem Diels-Alder/aromatization reactions.