Phosphonylated azaheterocycles are an important class of compounds with high biological potential as conformationally restricted bioisosteres of amino acids. Therefore, it is of interest to synthesize conformationally constrained amino phosphonates. We wanted to investigate possible routes via ring opening of α-amino phosphonates with an oxanorbornene skeleton, as these can be synthesized with high stereoselectivity. This was achieved using different Lewis acids, leading to a range of products. The reaction with TiCl4 and FeCl3 was modelled at a DFT level of theory to get insight in the pathways towards the corresponding products. To ease the work up, the Fe(III) catalyst was coated on montmorillonite clay, but this accelerated aromatization after ring opening. Quenching the FeCl3 catalyzed reaction mixture on celite caused complete aromatization.
膦酰化氮杂环是一类重要的化合物,具有作为
氨基酸构象限制的
生物等排体的高
生物潜力。因此,合成构象受限的
氨基膦酸盐是很有意义的。我们想要研究通过具有氧杂
降冰片烯骨架的 α-
氨基膦酸酯开环的可能途径,因为它们可以以高立体选择性合成。这是通过使用不同的
路易斯酸实现的,从而产生了一系列产品。在 DFT 理论
水平上对 TiCl4 和 FeCl3 的反应进行建模,以深入了解相应产物的途径。为了简化工作,将 Fe(III) 催化剂涂覆在
蒙脱石粘土上,但这加速了开环后的芳构化。在
硅藻土上猝灭 FeCl3 催化的反应混合物导致完全芳构化。