Visible-Light-Activated Catalytic Enantioselective β‑Alkylation of α,β-Unsaturated 2‑Acyl Imidazoles Using Hantzsch Esters as Radical Reservoirs

An efficient and practical method for the enantioselective β-functionalization of α,β-unsaturated 2-acyl imidazoles is described. The method uses a previously devised chiral-at-metal rhodium catalyst (Λ-<b>RhS</b>, 4 mol %) along with Hantzsch ester derivatives as alkyl radical sources. The rhodium complex exerts a dual role as the visible-light-absorbing unit upon substrate binding and as the asymmetric catalyst. The method provides up to quantitative yields with excellent enantioselectivities up to 98% ee and can be classified as a redox-neutral, electron-transfer-catalyzed reaction

Preferential Mitochondrial Localization of a Goniothalamin Fluorescent Derivative

A fluorescent 2,1,3-benzothiadiazole-containing goniothalamin derivative, BTD−GTN (<b>1</b>), has been synthesized and successfully tested in bioimaging experiments in live cells. The fluorescent compound proved to be capable of transposing the cell membranes, indicating its subcellular localization. The use of the benzothiadiazole core as the fluorophore revealed the favored localization of the GTN analogue <b>1</b> in the cytoplasm of live cells, preferentially in the mitochondria, in line with previous results that indicated the loss of mitochondrial transmembrane potential upon treatment with GTN. The results described herein highlight the potential of the BTD–GTN hybrid structures for future studies regarding the cellular mechanism of action of this family of compounds

Catalytic Enantioselective Allylations of Acetylenic Aldehydes via 2‑Propanol-Mediated Reductive Coupling

Cyclometalated π-allyliridium <i>C,O</i>-benzoates modified by (<i>S</i>)-SEGPHOS or (<i>S</i>)-Cl,OMe-BIPHEP catalyze enantioselective 2-propanol-mediated reductive couplings of diverse nonmetallic allyl pronucleophiles with the acetylenic aldehyde TIPSCCCHO. Absolute stereochemistries of the resulting secondary homoallylic–propargylic alcohols were assigned using Rychnovsky’s competing enantioselective conversion method