A Novel Synthetic Strategy Of C3-spirooxindole

OBJECTIVE:Taking a tetra-substituted oxindole olefin as substrate to synthesize multi-substituted,three-and five-membered spirooxindoles containing adjacent quaternary carbon centers via sulfur ylide.Otherwise,we hoped to develop a synthetic strategy to control the chemoselectivity between cyclopropane-and tetrahydrofuran-fused spirocyclic oxindole,and further enriching the molecular library of spirooxindoles.METHODS:It was conducted by[2+1]and[4+1]cyclic reactions of sulfur ylide chemistry to synthesis spirooxindoles,which containing vicinal quaternary carbon centers.And besides,installing different protecting groups on the tetra-substituted substrate makes the synthesis chemoselective.Finally,detecting the compounds'chemical structure by ¹H-NMR,¹³C-NMR,HRMS and X-Ray single crystal etc.RESULTS:1.Under the established conditions,cyclopropane-and tetrahydrofuran-fused spirooxindole containing adjacent quaternary carbon centers with 90%yield and high diastereoselectivity 20:1,which highlight the synthesis strategy's regioselectivity,chemoselectivity and diastereoslectivity;2.We totally synthesized 46 unreported compounds,and after ¹H-NMR,¹³C-NMR,HRMS analysis,the structures of the target products were determined to be in line with expectation;3.The relative configurations of the compounds 6r and 10a were detected by single crystal diffraction respectively,and the others'were determined by analogy;CONCLUSION:The synthetic strategy not only successfully constructed a series of multi-functional spirooxindole with conscious quaternary carbon centers,but also achieved the control of chemoselectivity between cyclopropane-and tetrahydrofuran-fused spriocyclic oxime by installing different protecting groups.