Iridium-catalyzed Highly Selective Reduction Of Nitroolefin In Aqueous Phase

Nitroalkanes are indispensable synthetic precursors and building blocks in organic synthesis.The chemoselective reduction of nitroalkenes,which can be facilely prepared by condensation of aldehydes/ketones with simple nitroalkanes,represents one of the most important and convenient accesses to nitroalkanes.Although some elegant and efficient reductions of nitroalkenes to nitroalkanes were realized,it is still a challenge to develop a green and highly efficient reduction of diversely substituted nitroalkenes to nitroalkanes with one versatile catalyst.In this dissertation,we report an iridium-catalyzed highly chemoselective and efficient transfer hydrogenation reduction of structurally diverse nitroalkenes is realized at very low catalyst loading(S/C=up to 10000 or 20000),using formic acid or sodium formate as traceless hydride donor in water.Excellent functionality tolerance is also observed.The turnover number and turnover frequecy of the catalyst reach as high as 18600 and 19200 mol·mol-1 h-1,respectively.Inert atmosphere protection is unnecessary.The pH value is a key factor to accomplish the complete conversion and excellent chemoselectivity.Purification of products is achieved by simple extraction without column chromatography.The reduction procedure is facilely amplified to 10-gram scale at 10000 S/C ratio,which shows excellent industrial application prospect.