Applications Of HR/MAS NMR In Combinatorial Chemistry

Combinational chemistry provides a new technique for synthesis and screening of compound libraries. High quality compound library depends on the perfect means of synthesis, analysis and purification. High-resolution magic angle spinning (HR/MAS) NMR has been used to perform fully structural determinations and conformational analysis of compounds attached onto solid-polymer support since 1990.Part I: HR/MAS NMR was applied in the field of combinational chemistry1. Influence of resins, solvents and temperatures upon the HR/MAS NMR of solid-phase synthesisFmoc-L-Ser(OtBu)-OH was coupled to resins. General conditions that affect HR/MAS NMR were studied in this paper including five resins, five solvents and temperatures. The results demonstrated that both resin and solvent are critical factors influencing ¹H line widths. Tenta Gel S NH₂ resins, which have the longest tethers and the most mobile moieties, provided the narrowest line-widths. CDCl₃ is a good choice of solvent due to cheap and its easy evaporative removal. Additionally, ¹H line widths don't vary with the temperatures.2. Solid-phase synthesis of O-glycosylated Fmoc protected amino acids and analysis by the HR/MAS NMRSolid-phase synthesis of glycopeptides library has been a hot topic. Fmoc protected amino acids bound to Tenta Gel S NH₂ resin are successfully O-glycosylated with a 7 peracetylated glycosyl trichloroacetimidates. The glycosylation reaction was monitored by the HR/MAS NMR. Furthermore, proton singlets of Fmoc group were treated as internal standard because of their station in both starting material and product. The increasing singlets of protons from acetyl...