Department of Chemistry, Indian Institute of Technology, Kanpur 208016, India.
J Org Chem. 2023 Apr 7;88(7):4504-4518. doi: 10.1021/acs.joc.2c03093. Epub 2023 Mar 27.
Activated aziridines react with propargyl alcohols in the presence of Zn(OTf) as the Lewis acid catalyst following an S2-type ring-opening mechanism to furnish the corresponding amino ether derivatives. Those amino ethers further undergo intramolecular hydroamination via cyclization in the presence of Zn(OTf) as the catalyst and tetrabutylammonium triflate salt as an additive under one-pot two-step reaction conditions. However, for nonracemic examples, ring-opening and cyclization steps were conducted under two-pot conditions. The reaction works well without any additional solvents. The final 3,4-dihydro-2-1,4-oxazine products were obtained with 13 to 84% yield and 78 to 98% enantiomeric excess (for nonracemic examples).
活化的氮丙啶在 Lewis 酸催化剂 Zn(OTf)的存在下与丙炔醇反应，遵循 S2 型开环机理，生成相应的氨基醚衍生物。这些氨基醚在 Zn(OTf)作为催化剂和四丁基三氟甲磺酸铵盐作为添加剂的存在下，进一步通过环化进行分子内氢胺化，在一锅两步反应条件下进行。然而，对于非外消旋的例子，开环和环化步骤在两釜条件下进行。反应在无需任何额外溶剂的情况下进行得很好。最终的 3,4-二氢-2-1,4-恶嗪产物的收率为 13%至 84%，对映体过量值为 78%至 98%（对于非外消旋的例子）。
