Investigation of the [1,5]-hydride shift as a route to nitro-Mannich cyclisations

摘要: Conditions were found for the [1,5]-hydride shift nitro-Mannich reaction that led to synthesis of 2,3-disubstituted tetrahydroquinolines. Two simple cyclic amine substrates gave diastereomerically pure rearranged products in 65 and 90% yields by refluxing HFIP. A more general procedure used Gd(OTf)3 as a catalyst successfully other acyclic amines 42–84% yield with diastereomeric ratios 75:25 >95:5 favour anti-diastereoisomer (9 examples). examples sulphur containing heterocycles lower 9 25%. Electron withdrawing substituents shown have deleterious effect on success reaction. The results indicated limitation respect stability intermediate iminium ion.