The aerobic dehydrogenative lactonization
of alkenoic acids facilitated by a cooperative nonmetallic catalyst
pair is reported. The title procedure relies on the adjusted interplay
of a photoredox and a selenium-π-acid catalyst, which allows
for the regiocontrolled construction of five- and six-membered lactone
rings in yields of up to 96%. Notable features of this method are
pronounced efficiency and practicality, good functional group tolerance,
and high sustainability, since ambient air and visible light are adequate
for the clean conversion of alkenoic acids into their respective lactones.
The title method has been used as a case study to elucidate the general
mechanistic aspects of the dual selenium-π-acid/photoredox catalysis.
On the basis of NMR spectroscopic, mass spectrometric, and computational
investigations, a more detailed picture of the catalytic cycle is
drawn and the potential role of trimeric selenonium cations as catalytically
relevant species is discussed.
A catalytic regime for the direct phosphatation of simple, non-polarized alkenes has been devised that is based on using ordinary, non-activated phosphoric acid diesters as the phosphate source and O as the terminal oxidant. The title method enables the direct and highly economic construction of a diverse range of allylic phosphate esters. From a conceptual viewpoint, the aerobic phosphatation is entirely complementary to traditional methods for phosphate ester formation, which predominantly rely on the use of prefunctionalized or preactivated reactants, such as alcohols and phosphoryl halides. The title transformation is enabled by the interplay of a photoredox and a selenium π-acid catalyst and involves a sequence of single-electron-transfer processes.
This study describes for the first time the vital role of GDF15 both in tumorigenesis and in radioresistance of OSCC cells. With its anti-apoptotic effects, GDF15 possibly promotes tumor progression and might protect carcinoma cells against irradiation effects. Consequently, GDF15 may be a promising therapeutic target in oral cancer.
The facile synthesis of aminoallenes, accomplished by a selenium‐π‐acid‐catalyzed cross‐coupling of an N‐fluorinated sulfonimide with simple, non‐activated alkynes, is reported. Until now, aminoallenes were difficult to be accessed by customary means, inasmuch as pre‐activated and, in part, intricate starting materials were necessary for their synthesis. In sharp contrast, the current study shows that ordinary internal alkynes can serve as simple and readily available precursors for the construction of the aminoallene motif. The operating reaction conditions tolerate numerous functional groups such as esters, nitriles, (silyl)ethers, acetals, and halogen substituents, furnishing the target compounds in up to 86 % yield.
A new organocatalytic protocol for the aerobic dehydrogenative allylation of alcohols using non-activated alkenes as the allylating reagent and ambient air as the terminal oxidant is established. Mechanistically, the procedure relies on the interplay of a diselane and a photoredox catalyst by means of a light-induced electron transfer process. Under optimized conditions, a broad range of both cyclic and acyclic ethers is accessed with very high functional group tolerance and excellent regioselectivity.
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