DIBAL-H-mediated N-deacetylation of tertiary amides: synthesis of synthetically valuable secondary amines.

A rapid DIBAL-H-mediated N-deacetylation of tertiary amides is described under mild conditions, affording synthetically valuable secondary amines in good to excellent yields.

N-Heterocyclic carbene-catalysed homoenolate addition reaction to 3-cyano-2-imino-2H-chromenes: synthesis of C4-functionalized 2-amino-3-cyano-4H-chromene.

A diastereoselective N-heterocyclic carbene-catalysed reaction between enal and 3-cyano-2-imino-2H-chromene is described for accessing a new type of C4-functionalized 2-amino-3-cyano-4H-chromene. A wide variety of enals and iminochromenes afforded the desired homoenolate addition product 2-amino-4H-chromenes in good yields and with moderate to good diastereoselectivities.

HFIP-promoted halo-carbocyclizations of N- and O-tethered arene-alkene substrates to access all halo (X = Br, I, Cl)-functionalized tetrahydroquinoline and chroman cores.

A new method for the stereoselective metal-, additive- and oxidant-free Friedel-Crafts-type halo-carbocyclization of N- and O-tethered arene-olefin substrates is reported, involving reaction with a suitable electrophilic halogenating reagent (NXS/DCDMH) in hexafluoroisopropanol. All halo (X = Br, I, Cl)-functionalized tetrahydroquinolines and chromans were obtained in excellent yields and with high levels of diastereocontrol (dr = >99 : 1), and these products were successfully transformed into synthetically useful compounds such as dihydroquinolines and partial or full azahelicene compounds.

Highly Selective and Catalytic C-N Bond Cleavage of Tertiary Sulfonamides: Scope and Mechanistic Insight.

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.

Fe(OTf)3-catalysed Friedel-Crafts reaction of benzenoid arenes with α,ß-unsaturated carbonyl compounds: easy access to 1,1-diarylalkanes.

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,ß-unsaturated carbonyl compounds. This reaction afforded ß,ß-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.