Mang Wang

Electrophilic N‑Trifluoromethylation of N−H Ketimines

A direct N-trifluoromethylation method has been developed by the use of the in situ generated [ArICF3](+) species as the electrophilic trifluoromethyl source. Upon treatment of N-H ketimines with Ruppert-Prakash reagent in the presence of PhI(OAc)2 and KF, or with Tognis reagent II catalyzed by copper salt, N-trifluoromethylated imine products were obtained in moderate to good yields.

Hydrobromic acid-catalyzed Friedel–Crafts type reactions of naphthols

Catalyzed by 10 mol% of hydrobromic acid, hydroxyalkylation and allylation-iodocyclization of naphthols proceeded smoothly under mild conditions. In contrast, other Bronsted acids tested, including HCl, HI, HBF4, HPF6, TFA, PTSA, H2SO4, TfOH etc., are almost ineffective under identical conditions or require harsh reaction conditions.

Palladium-catalyzed oxidative C–O cross-coupling of ketene dithioacetals and carboxylic acids

Direct oxidative C–O cross-coupling reaction between active alkenes and carboxylic acids is presented. By utilizing Pd(OAc)2 as a catalyst and PhI(OAc)2 as an oxidant, ketene dithioacetals were smoothly acyloxylated in carboxylic acid–water solution, affording a variety of vinyl esters in a highly selective way with high efficiency and good functional group tolerance. A plausible mechanism is proposed that features a vinyl iodonium species as key intermediate.

Synthesis of 2,2-Difluorinated 4-Isoflavanols/4-Thioisoflavanols via a Base-Catalyzed [4 + 2] Annulation Reaction of gem-Difluoroolefins

DBU-catalyzed sequential intermolecular and intramolecular nucleophilic addition reactions between gem-difluoroolefins and o-hydroxy/mercapto benzaldehydes have been developed to provide a [4 + 2] annulation strategy for facile synthesis of gem-difluorinated isoflavanol derivatives. The competitive addition-elimination reaction of gem-difluoroolefins with nucleophiles was avoided under mild conditions, affording 2,2-difluorinated 4-isoflavanols or 2,2-difluoriated 4-thioisoflavanols in good to excellent yields.