Chemistry Department, Hamilton College, 198 College Hill Road, Clinton, NY 13323, USA.
Rigaku Oxford Diffraction, 9009 New Trails Drive, The Woodlands, TX 77381, USA.
Molecules. 2018 Feb 14;23(2):413. doi: 10.3390/molecules23020413.
-Substituted pyridinium salts constitute one of the most valuable reagent classes in organic synthesis, due to their versatility and ease of use. Herein we report a preliminary synthesis and detailed structural analysis of several -(1-ethoxyvinyl)pyridinium triflates, an unusual class of pyridinium salts with potentially broad use as a reagent in organic synthesis. Treatment of pyridines with trifluoromethane sulfonic acid and ethoxyacetylene generates stable, isolable adducts which have been extensively characterized, due to their novelty. Three-dimensional structural stability is perpetuated by an array of C-H•••O hydrogen bonds involving oxygen atoms from the -SO₃ groups of the triflate anion, and hydrogen atoms from the aromatic ring and vinyl group of the pyridinium cation. Predictions from density functional theory calculations of the energy landscape for rotation about the exocyclic C-N bond of 2-chloro-1-(1-ethoxyvinyl)pyridine-1-ium trifluoromethanesulfonate () and 1-(1-ethoxyvinyl)pyridine-1-ium trifluoromethanesulfonate () are also reported. Notably, the predicted global energy minimum of was nearly identical to that found within the crystal structure.
取代的吡啶鎓盐是有机合成中最有价值的试剂类别之一，因为它们具有多功能性和易用性。在此，我们报告了几种 -(1-乙氧基乙烯基)吡啶𬭩三氟甲磺酸酯的初步合成和详细结构分析，这是一类不寻常的吡啶鎓盐，作为有机合成中的试剂具有广泛的潜在用途。三氟甲磺酸与乙炔基乙酯作用于吡啶，生成稳定的、可分离的加合物，由于其新颖性，对其进行了广泛的表征。三维结构稳定性通过一系列涉及三氟甲磺酸阴离子 -SO3 基团中的氧原子以及吡啶鎓阳离子的芳环和乙烯基上的氢原子的 C-H•••O 氢键来维持。还报告了关于 2-氯-1-(1-乙氧基乙烯基)吡啶-1-鎓三氟甲磺酸酯 ()和 1-(1-乙氧基乙烯基)吡啶-1-鎓三氟甲磺酸酯 ()中环外 C-N 键旋转的密度泛函理论计算的能量景观预测。值得注意的是，预测的全局能量最小值与晶体结构中发现的几乎相同。
