Synthesis of 2,4,5-trisubstituted oxazoles through tin(ⅳ) chloride-mediated reaction of frans-2-aryl-3-nitro-cyclopropane-1,1-dicarboxylates with nitriles

摘要

Trans-2-Aryl-3-nitro-cyclopropane-1,1-dicarboxylates when reacted with nitrites in the presence of tin(Ⅳ) chloride afford 2,4,5-trisubstituted oxazoles in good to excellent yields. The reactions take place through in situ generation of aroylmethylidene malonates from the cyclo-propanes, followed by conjugate addition of nitriles to the malonates to form nitrilium ion intermediates and subsequent cyclisation.