Although the construction of axially chiral C−C bonds leading to the atroposelective synthesis of biaryls and allied compounds are well‐known, the related synthesis of compounds bearing axially chiral C−N bonds are relatively rare. Described herein is the N‐heterocyclic carbene‐catalyzed atroposelective synthesis of N‐aryl succinimides having an axially chiral C−N bond via the desymmetrization of N‐aryl maleimides. The NHC involved intermolecular Stetter‐aldol cascade of dialdehydes with prochiral N‐aryl maleimides followed by oxidation afforded N‐aryl succinimides in good yields and ee values. Preliminary studies on rotation barrier for the C−N bond, the temperature dependence, and detailed DFT studies on mechanism are also provided.

The [3 + 3] annulation of α,β-unsaturated aldehydes with 2-substituted 1,4-naphthoquinones allowing the facile synthesis of functionalized dihydrocoumarins catalyzed by N-heterocyclic carbene (NHC) is reported. The initially formed NHC-homoenolates underwent an efficient Michael–isomerization–lactonization cascade to furnish the products. Preliminary studies on mechanism shed light on the homoenolate pathway over the intermediacy of the α,β-unsaturated acylazolium intermediates. Moreover, using chiral NHCs, the desired products were formed in up to 49% yield and 99:1 er.

Unless otherwise specified, all reactions were carried out under an atmosphere of argon in flame-dried reaction vessels with Teflon screw caps. Mesitylene was purchased from commercial sources and stored under argon over 4 Å molecular sieves. The 2-bromoenals were synthesized from the corresponding -unsaturated aldehydes following the literature procedure. 1 All the thioamide derivatives were prepared following the literature procedure. 2 The triazolium salt C was synthesized following the literature procedure. 3 K2CO3 was purchased from SD-Fine. Analytical thin layer chromatography was performed on TLC Silica gel 60 F254. Visualization was accomplished with short wave UV light or KMnO4 staining solutions followed by heating. Flash chromatography was performed on silica gel (230-400 mesh) by standard techniques eluting with Pet. Ether-EtOAc solvent system. All compounds were fully characterized. 1 H and 13 C NMR spectra were recorded on Bruker AV 400 and Bruker Ultra shield spectrometer in solvents as indicated. Chemical shifts (δ) are given in ppm. The residual solvent signals were used as references and the chemical shifts converted to the TMS scale (CDCl3: δH = 7.26 ppm, δC = 77.16 ppm). Infrared (FT-IR) spectra were recorded on a Perkin Elmer Spectrum BX spectrophotometer, ν-max in cm-1. Optical rotations were measured on JASCO P-2000 polarimeter at room temperature using 50 mm cell of 1 mL capacity. HRMS (ESI) data were recorded on a Micromass Q-TOF Micro instrument. HPLC analysis was performed on Agilent Technologies 1260 Infinity II with UV detector.

Chiral NHC-catalyzed kinetic resolution of N-aryl aminomaleimides allowing the synthesis of C–N axially chiral N-aryl aminomaleimides via remote chirality control is presented. The catalytically generated α,β-unsaturated acylazoliums from 2-bromoenals underwent selective [3 + 3] annulation with one of the enantiomers of maleimide to furnish fused-dihydropyridinone (bearing axial/central chirality, up to 6:1 dr, >99:1 er) leaving the enantioenriched opposite enantiomer (up to >99:1 er). Studies on C–N bond rotation barrier and dependence on temperature are also provided.

Although the atroposelective synthesis of biaryls and related compounds bearing axially chiral C−C bonds is wellknown, the synthesis of axially chiral C−N bond-containing compounds is relatively less explored, and the construction of axially chiral N−N bonds has received only scant attention. Demonstrated herein is the N-heterocyclic carbene (NHC)-catalyzed selective amidation reaction, leading to the atroposelective synthesis of N−N axially chiral 3-amino quinazolinones. The NHC-catalyzed reaction of quinazolinones containing a free N−H moiety with α,β-unsaturated aldehydes under oxidative conditions furnished the atropisomeric quinazolinone derivatives under mild conditions and broad scope. Preliminary studies on experimental and density functional theory-based N−N rotational barrier determination are also presented.