gpss_a_1417298_sm1480.docx (12.53 MB)
TiCl2(OTf)-SiO2: A solid stable lewis acid catalyst for Michael addition of α-Aminophosphonates, Amines, Indoles and Pyrrole
Version 2 2018-01-16, 15:24
Version 1 2017-12-15, 21:08
journal contribution
posted on 2018-01-16, 15:24 authored by Habib Firouzabadi, Naser Iranpoor, Soghra FarahiTiCl2(OTf)-SiO2 is simply prepared by immobilization of TiCl3(OTf) on silica gel surface and introduced as a non-hygroscopic Lewis acid catalyst for C-N and C-C bond formation via Michael addition reaction. A variety of structurally diverse nitrogen nucleophiles including α-aminophosphonates, aliphatic and aromatic amines and imidazole were evaluated as Michael donors. Friedel–Crafts alkylation of indoles and pyrrole was also investigated through Michael addition reaction in the presence of TiCl2(OTf)-SiO2 as a catalyst. The reactions were conducted at room temperature or 60 °C under solvent-free conditions and the desired Michael adducts were obtained in high to excellent yields.