Go with the flow: A simple flow reactor has been developed to accommodate highly absorbing [RuL3]2+ photosensitizers for light‐starved photoredox reactions (see picture). The use of vessels having a thin diameter increases the efficiency of the reaction. This methodology has been applied to the divergent synthesis of C‐glycoconjugates.

Reaction of biphepPt(CO 3 ) (biphep ) 2,2′-bis(diphenylphosphino)-1,1′-biphenyl) with BINOL or HN(Tf)CHPhCHPhOH (TfNO) yielded square-planar biphepPtX 2 (X 2 ) BINOL, N(Tf)CHPhCHPhO) complexes as a mixture of diastereomers (∼1:1). BiphepPtCl 2 also reacted with Na 2 BINOL to generate biphepPt(BINOL) as a 1:1 mixture of diastereomers. With racemic BINOL or TfNO ligands, the mixtures were prone to isomerize to thermodynamic diastereomer mixtures (BINOL, 95:5; TfNO, >97:3) by an X 2 -X 2 ligand-ligand exchange mechanism that was rapid at room temperature. With enantiopure ligands the X 2 -X 2 ligandligand exchange process was degenerate and nonproductive. However, thermolysis of 1:1 mixtures of enantiopure biphepPt(BINOL) diastereomers (92-122 °C) cleanly established thermodynamic equilibrium by a process that involves biphenyl atropisomerism (∆H q ) 27(2) kcal mol -1 , ∆S q ) -5(5) eu). Two mechanisms for this process were considered, concerted stereoinversion via a planar seven-membered metallacycle, and one-arm-off prior to a biphenyl isomerization (anti disposed PPh 2 units). In pyridine, a third mechanism for atropisomerism was identified and proposed to involve a five-coordinate pyridine intermediate (not observed) with an enhanced phosphine dissociation rate. Pyridine lowered the isomerization temperature of enantiopure complexes by ∼50 °C. X-ray structures of the thermodynamically favored biphepPt(TfNO) ((()-4a) and the thermodynamically less favored biphepPt(BINOL) (λ(S)-5b) diastereomers were obtained, and a stereochemical model to explain the diastereoselectivity was formulated.

A high-yielding fluorination of (triphos)Pt-R+ has been achieved using an array of F+ sources, with XeF2 yielding R–F in minutes. The C–F coupling proved to be a stereoretentive process that proceeds via a concerted reductive elimination from a putative dicationic Pt(IV) center. The larger the steric congestion of the (triphos)Pt–Csp3+ complexes, the more efficient the fluorination, seemingly a result of sterically accelerated C–F reductive elimination along with simultaneous deceleration of its competing processes (β-H elimination).

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