Controllable room-temperature visible-light activated nitroxide (TEMPO)-release from benzimidazolequinone alkoxyamines and bis-alkoxyamines.

Isosorbide was functionalized with furoxan for the first time to give adducts that release nitric oxide up to 7.5 times faster than the commercial vasodilator, isosorbide-5-mononitrate (Is5N). The synthesis was facilitated by MeMgCl-mediated selective acetylation of isosorbide or selective deacetylation of isosorbide-2,5-diacetate, which was rationalized in terms of a more stable 5-alkoxide magnesium salt using DFT. Isosorbide-furoxans are safer to handle than Is5N due to greater thermal stability.

1,1,3,3‐Tetramethylisoindolin‐2‐yloxyl (TMIO) is a well‐known stable 2,3‐dihydroisoindoline aminoxyl radical, which is thermally generated (at >100 °C) from literature alkoxyamine derivatives. Herein is the synthesis of visible light activated benzimidazolequinone alkoxyamines of TMIO using oxidative methods and the first room temperature nitroxide‐exchange experiments with 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) analogues. For the alkoxyamine TMIO‐Vis dissociation rate constants are provided using TEMPO and oxygen as radical traps.

Ring-fused benzimidazolequinones are well-known anti-tumour agents, but dimeric ring-fused adducts are new. The alicyclic [1,2-a] ring-fused dimethoxybenzimidazole-benzimidazolequinone (DMBBQ) intermediate allows late-stage functionalization of bis-p-benzimidazolequinones. DMBBQs are chlorinated and brominated at...

Selectfluor (1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate)) substitutes the TEMPO free radical with fluorine on 4,7-dimethoxy-1-methyl-2-{[(2,2,6,6-tetramethylpiperidin-1-yl)oxy]methyl}-1H-benzimidazole to give the title compound in a 77% yield. A mechanism is proposed for the formation of this novel methylene fluoride.