Herein, an effective kinetic resolution (KR) of racemate 2-aryl-3-nitro-2H-chromenes to afford synthetically valuable chromans and 2H-chromenes through an NHC-bound acyl azolium homoenolate pathway has been demonstrated.

A diastereoselective N-heterocyclic carbene-catalysed reaction between enal and 3-cyano-2-imino-2H-chromene is described to accessing a new type of C4-functionalized 2-amino-3-cyano-4Hchromene. A wide variety of enals and iminochromenes afforded the desired homoenolate...

A highly chemoselective C–N bond cleavage reaction of p-methoxybenzyl- (PMB), 3,4-dimethoxybenzyl- (DMB), or cinnamyl-substituted tertiary sulfonamides in the presence of catalytic Bi­(OTf)3 is presented. A wide range of sulfonamide substrates smoothly furnished the corresponding C–N bond cleavage products in good to excellent yields. Great efforts have been made to obtain insights into the reaction mechanism based on a series of control experiments and mass spectroscopy.

Here reports a highly regio-and diastereoselective haliranium ion-induced intermolecular Friedel-Crafts reaction of α,β-unsaturated carbonyl compounds in HFIP. The operationally simple and mild method affords the synthetically useful β,β-diarylated α-halo carbonyl compounds in good yields after a very short reaction time. As an application, a few examples of β,βdiarylated olefins are prepared in excellent yields. Based on the experimental results and a qualitative study of 1D-NMR-experiments, a plausible reaction mechanism is proposed.

A simple and efficient method for the synthesis of 1,1-diarylalkanes via the Friedel–Crafts-type alkylation reaction of electron-rich arenes with cinnamic acid ester derivatives or chalcones is reported. Iron triflate has been found to be the best catalyst for the Friedel–Crafts-type alkylation reaction with α,β-unsaturated carbonyl compounds. This reaction afforded β,β-diaryl carbonyl compounds in good yields (65–93%) and with excellent regioselectivities. Remarkably, this method is also compatible with a variety of indoles to provide 3-indolyl-aryl carbonyl compounds in excellent yields. Great efforts have been made to deduce a plausible reaction mechanism based on isotopic labelling experiments.