Herein, we report a method that uses antifungal tavaborole
as a
co-catalyst for direct α-C–H alkylation of structurally
diverse alcohols through photoredox catalysis. The protocol features
mild conditions, remarkable scope, and wide functional group tolerance,
which allows for the construction of a wide array of highly functionalized
alcohols, including homoserine derivatives and C-glycosyl
amino acids. We also demonstrate the synthetic applications of this
methodology to the late-stage functionalization of pharmaceuticals
and natural products.
Understanding the rich and competing electronic orders in cuprate superconductors may provide important insight into the mechanism of high-temperature superconductivity. Here, by measuring Bi2Sr2CaCu2O8+x in the extremely underdoped regime, we obtain evidence for a distinct type of ordering, which manifests itself as resistance oscillations at low magnetic fields (≤10 T) and at temperatures around the superconducting transition. By tuning the doping level p continuously, we reveal that these low-field oscillations occur only when p < 0.1. The oscillation amplitude increases with decreasing p but the oscillation period stays almost constant. We show that these low-field oscillations can be well described by assuming a periodic superconducting structure with a mesh size of about 50 nm. Such a charge order, which is distinctly different from the well-established charge density wave and pair density wave, seems to be an unexpected piece of the puzzle on the correlated physics in cuprates.
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