Engineering N-(2-pyridyl)aminoethyl alcohols as potential precursors of thermolabile protecting groups
作者:Marcin K. Chmielewski、Ewa Tykarska、Wojciech T. Markiewicz、Wojciech Rypniewski
DOI:10.1039/c1nj20584f
日期:——
Crystal and NMR analyses of four precursors of N-(2-pyridyl) thermolabile protecting group (TPG) were carried out. Two torsion angles have been identified as indicators that predict the molecules' thermolabile properties. Conformation that minimizes the N1⋯C8 distance is crucial for thermocyclisation. Nucleophilicity of the pyridyl ring is the driving force for the reaction but it is insufficient for thermocyclisation which is dominated by the molecules' ability to adopt a favourable conformation. The pKa value was recorded for all analyzed N-(2-pyridyl)aminoethyl alcohols. However, its effect is small in the determination of thermolability. Based on the analysis that we carried out, N-benzyl N-(2-pyridyl)aminoethyl was selected as a potential precursor of thermolabile carbonate of TPG.
对四个N-(2-吡啶基)热敏保护基(TPG)前体进行晶体和NMR分析。确定了两个扭转角作为预测分子热敏特性的指标。最小化N1⋯C8距离的构象对热环化至关重要。吡啶环的亲核性是反应的驱动力,但对于热环化来说,这是不够的,因为热环化主要受分子采用有利构象的能力主导。对所有分析过的N-(2-吡啶基)氨基乙醇的pKa值进行了记录。然而,这一点对热稳定性的影响较小。根据我们进行的分析,选择N-苄基N-(2-吡啶基)氨基乙醇作为潜在的TPG热敏碳酸酯前体。