New Method For Formation Of Spiroxindoles Iodonium From N-substituted 3-oxopentanediamides Via PhI(OCOCF3)2-Mediated Oxidative Cascade Reactions

Aryliodonium salts,a class of non-metal oxidants,with numerous applications as synthetic reagents and biologically active compounds,due to the ready accessibility,high reactivity,and mild toxicity.At the same time,spirooxindoles are important mother nucleus structure,many of their derivatives show a variety of biological activities,such as inhibiting cell growth,anti-cancer,anti-inflammatory and analgesic and antihypertensive effect,futher more,they can be used as potential drugs for clinical treatment.Herein,we developed an oxidative cascade reaction of N-Substituted3-Oxopentanediamides mediated by PIFA.It mainly includes four types:1)PIFA-mediatedintramolecularC?sp³?–C?sp²?bond-formingreactions.2)PIFA-mediated intramolecular C?sp²?–O bond formation.3)PIFA-mediated intermolecular C-I bond formation.4)Based on these,we also further investigated the transformations of spirooxindole iodonium salt 110a.We chose N-substituted 3-oxopentanediamides 109 as substrates,PIFA as oxidant,and spirooxindoles iodonium 110 have been synthesized in CH₃NO₂ under 0^oC.Aiming to test the selectivity of the transformation and improve the diversity of the substrates,we synthesized an asymmetric amide?109q?and carried out the reactions under the standard conditions.A mixture of two isomers was respectively isolated in 38%and 32%yields,respectively.In the presence of Cu?OTf?₂,N-Methylisatin have been offered by?1'-Methyl-5-?methyl?phenyl?amino?-2',3-dioxo--3H-spiro[furan-2,3'-indolin]-4-yl??phenyl?iodonium 2,2,2-trifluoroacetate.All the compounds have been characterized by ¹H NMR,¹³C NMR,¹⁹F NMR and HRMS.The new method compromises the merits of the readily availability of the starting materials,diversity of the substrates,the mild reaction conditions and the novelty of the products.