Search results for "chiral resolution"
showing 2 items of 12 documents
Asymmetric Synthesis of Chiral Bimetallic [Ag28Cu12(SR)24]4– Nanoclusters via Ion Pairing
2016
In this work, a facile ion-pairing strategy for asymmetric synthesis of optically active negatively charged chiral metal nanoparticles using chiral ammonium cations is demonstrated. A new thiolated chiral three-concentric-shell cluster, [Ag28Cu12(SR)24]4–, was first synthesized as a racemic mixture and characterized by single-crystal X-ray structure determination. Mass spectrometric measurements revealed relatively strong ion-pairing interactions between the anionic nanocluster and ammonium cations. Inspired by this observation, the as-prepared racemic mixture was separated into enantiomers by employing chiral quaternary ammonium salts as chiral resolution agents. Subsequently, direct asymm…
Cyclic Sulfonimidates by Dynamic Diastereomer-Differentiating Cyclisation: Large-Scale Synthesis and Mechanistic Studies
2001
A dynamic diastereomer differentiating cyclisation is the key step in a new large-scale synthesis of both enantiomers of the cyclic sulfonimidates 1 (Aldrich no. 54099-4) and ent-1 (Aldrich no. 54412-4). These are valuable starting materials in the asymmetric synthesis of chiral oxa- and azaheterocyclic compounds. NMR spectroscopic studies on the reacting system reveal N-chloro sulfinamides to be reactive intermediates in the oxidative chlorination of sulfinamides with tert-butyl hypochlorite and allow for the inspection of the configurational behaviour of the involved sulfonimidoyl chlorides and sulfonimidoyl bromides.