One-electron oxidation of two series of diaryldichalcogenides (C6F5E)2 (13a–c) and (2,6-Mes2C6H3E)2 (16a–c) was studied (E = S, Se, Te). The reaction of 13a and 13b with AsF5 and SbF5 gave rise to the formation of thermally unstable radical cations [(C6F5S)2]˙+ (14a) and [(C6F5Se)2]˙+ (14b) that were isolated as [Sb2F11]− and [As2F11]− salts, respectively. The reaction of 13c with AsF5 afforded only the product of a Te–C bond cleavage, namely the previously known dication [Te4]2+ that was isolated as [AsF6]− salt. The reaction of (2,6-Mes2C6H3E)2 (16a–c) with [NO][SbF6] provided the corresponding radical cations [(2,6-Mes2C6H3E)2]˙+ (17a–c; E = S, Se, Te) in the form of thermally stable [SbF6]− salts in nearly quantitative yields. The electronic and structural properties of these radical cations were probed by X-ray diffraction analysis, EPR spectroscopy, and density functional theory calculations and other methods.
Octahydroindolo[2,3-a]quinolizine ring system forms the basic framework comprised of more than 2000 distinct family members of natural products. Despite the potential applications of this privileged substructure in drug discovery, efficient, atom-economic and modular strategies for its assembly, is underdeveloped. Here we show a one-step build/couple/pair strategy that uniquely allows access to diverse octahydroindolo[2,3-a]quinolizine scaffolds with more than three contiguous chiral centers and broad distribution of molecular shapes via desymmetrization of the oxidative-dearomatization products of phenols. The cascade demonstrates excellent diastereoselectivity, and the enantioselectivity exceeded 99% when amino acids are used as chiral reagents. Furthermore, two diastereoselective reactions for the synthesis of oxocanes and piperazinones, is reported. Phenotypic screening of the octahydroindolo[2,3-a]quinolizine library identifies small molecule probes that selectively suppress mitochondrial membrane potential, ATP contents and elevate the ROS contents in hepatoma cells (Hepa1–6) without altering the immunological activation or reprogramming of T- and B-cells, a promising approach to cancer therapy.
24 December 2018 in The Journal of Organic Chemistry
Investigation of Capparis spinosa of Jordanian origin lead to isolation of two new compounds g -sitosterylglucoside-6'-octadecanoate ( 1 ) and 3-methyl-2-butenyl- g -glucoside ( 2 ). Linked Scan MS measurements were used to propose a mass fragmentation pattern for the alkaloid Cadabicine isolated here for the second time from nature.