One-step synthesis of inherently chiral p-tert-butylcalix[4]azacrown

A one-step procedure is developed to synthesize inherently chiral p-tert-butylcalix[4]azacrown 1 through etherification between p-tert-butylcalix[4]arene and compound 3, which can be amplifed to efficiently prepare more inherently cbiral calix[4]arenes in ABHH substitution pattern.

An Inherent Chiral Calix[4]arene Bearing Chiral Groups without Forming Sub-ring

The NMR spectra revealed that the calixarene frame of 1, 3-disubstituted calix[4]arenes beating optically active groups is asymmetric, even without the formation of a sub-ring. This inherent chirality arises from the interaction of the two chiral groups, which hinder the substituents＇ free rotation. Thus, these chiral calix[4]arenes display good chiral recognition ability.

Inherently Chiral 6,7-Diphenyldibenzo [e,g][1,4]diazocine: Enantioselective Synthesis and Application as a Ligand Platform

Inherently chiral 6,7-diphenyldibenzo[e,g][1,4]diazocine(DDD)has been synthesized enantioselectively for the first time via chiral phosphoric acid(CPA)-catalyzed cyclocondensation of readily available[1,1′-biphenyl]-2,2′-diamine(1a)and benzil(2a)in 82%yield,with 98%ee under mild reaction conditions.The strategy could also be applied to racemic biaryl diamines through kinetic resolution.The unexpectedly high interconversion energy barriers between the enantiomers(ΔG=39.5 kcal/mol)and the chemical stability rendered DDD an ideal platform for developing new chiral ligands and catalysts.Unique inherently chiralDDD-based phosphoramidites,phosphoric acid,mono-and diphosphine ligands were prepared from optically pure diphenol derivative DDDOL as a common precursor.Preliminary asymmetric reactions catalyzed by Pd or Rh in the presence of newly developed ligands exhibited comparable or even better enantioselectivities than the corresponding BINOLor SPINOL-derived ligands.Density functional theory calculation revealed the origin of the enantioselectivity during the process.

Catalytic Asymmetric Synthesis of Inherently Chiral Saddle- Shaped Dibenzo[b,fI[1,5]diazocines

Dibenzo[b,fi[1,5]diazocines are a class of eight-membered heterocycles,which exhibit unique rigid saddle-shaped structure and possess inherent chirality.In this study,we report a convenient and straightforward method for the catalytic enantioselective synthesis of these unique chiral molecules through chiral phosphoric acid-catalyzed dimerization of 2-acylbenzoisocyanates.Notably,the addition of corresponding 2-acylaniline as the co-catalyst significantly improved the efficiency of these reactions,and a simple phase separation operation resulted in products with excellent enantiopurity.Experimental studies were performed to elucidate the mechanism behind these reactions,leading to the proposal of a plausible reaction mechanism based on the study findings.