A highly reactive and robust chiral Brønsted acid catalyst, chiral N-triflyl thiophosphoramide, was developed. The first metal-free Brønsted acid catalyzed enantioselective protonation reaction of silyl enol ethers was demonstrated using this chiral Brønsted acid catalyst. The catalyst loading could be reduced to 0.05 mol % without any deleterious effect on the enantioselectivity.
A chiral Brønsted acid has been developed from cationic gold(I) disphosphine complex in the presence of alcoholic solvent and applied to enantioselective protonation reaction of silyl enol ethers of ketones. Various optically active cyclic ketones were obtained in excellent yields and high enantioselectivities including cyclic ketones bearing aliphatic substrates at the α-position. Furthermore, the application of this Brønsted acid was extended to the first Brønsted acid-catalyzed enantioselective protonation reaction of silyl enol ethers of acyclic substrates, regardless of their E/Z ratio.
The first metal-free thermal protodeboronation of ortho- and para-phenol boronic acids in DMSO was developed. The protodeboronation was successfully applied to the synthesis of ortho- and meta-functionalized phenols using the boronic acid moiety as a blocking group and a directing group, respectively. Mechanistic studies suggested that this protodeboronation proceeds through the coordination of water to the boron atom followed by σ-bond metathesis.
We report a new hole transporting material (HTM) based on [2,2]paracyclophane triarylamine. Due to its higher charge mobility compared with spiro-OMeTAD, the solar cell device incorporating the new HTM achieved a high photovoltaic performance with a PCE of 17.6%.
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