10.1002/ejoc.201101336
The research focuses on the short synthesis of chiral 4-substituted (S)-imidazolinium salts bearing sulfonates, which are precursors to N-heterocyclic carbene (NHC) ligands. These ligands are vital in catalytic chemistry, enhancing the activity and selectivity of metal catalysts in various transformations. The study details a one-pot reaction involving Boc-protected amino alcohols, 2-sulfobenzoic anhydride, and primary amines, leading to a diverse range of amidosulfonates. These are then converted to imidazolinium sulfonate zwitterions through a two-step process involving reduction with BH3·SMe2 and cyclisation with HC(OEt)3. The synthesized imidazolinium salts were characterized using X-ray crystallography and tested as catalysts in γ-selective reactions of allyl halides with Grignard reagents, showing high selectivity and enantiomeric enrichment in the products. The experiments utilized various analytical techniques such as NMR, IR spectroscopy, and HRMS for compound characterization, with the reactions' yields and enantiomeric excess (ee) determined by GC analysis using a Chiracil-Dex-CB column.
10.1002/ejoc.200400562
The research focuses on the synthesis of sulfonic acid libraries, specifically targeting the preparation of compound libraries for applications in drug screening, catalysis, and materials chemistry. The study explores the use of 2-sulfobenzoic acid anhydride and N-Boc-protected α-amino alcohols to synthesize zwitterionic esters and oxazoline sulfonic acid derivatives, which are further functionalized to sulfonamides. The purpose of this research is to develop a one-step synthesis method for these compounds, which are known to be potent pharmaceutical and catalytic ligand lead structures. The conclusions drawn from the research demonstrate the successful rapid synthesis of oxazolinesulfonic acids either through esters or directly from 2-sulfobenzoic acid anhydride and N-Boc-protected amino alcohols. Additionally, a useful displacement reaction was discovered, allowing access to diverse 2-amido-diamine benzenesulfonic acids, which is suitable for high-throughput library synthesis.
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