The Construction Of Carbon-Carbon Bonds And Carbon-Heteroatom Bonds Based On Organic Hypervalent Iodine(?) Reagents

Organic hypervalent iodine reagents as a kind of simple,eco-friendly and efficient reaction reagents have attracted much attention in recent decades.With the continuous development of this field,a variety of new organic hypervalent iodine reagents have emerged,and their role has become more and more important in organic synthesis chemistry.More importantly,the emergence of chiral hypervalent iodine reagents provides a novel and efficient method for the development of new asymmetric reactions.In this thesis,a series of novel and efficient methods to construct C-C,C-O,C-N and C-B bonds were developed by using the organic hypervalent iodine reagents preprared,such as iodobenzene diacids,hypervalent iodine(?)five-membered heterocycles,alkenyl(aryl)iodonium salts and various chiral iodobenzene(I/?)catalysts.A novel metal-free approach to directly synthesize?-acyloxy sulfides(32%-96%yields)from readily available alkyl sulfides by the combination of hypervalent(diacyloxyiodo)benzene and TBAB reagent has been achieved.Preliminary mechanism studies have shown that this reaction might be mainly attributed to the generation of the tetra-n-butylammonium[di(acyloxy)bromated(I)].Meanwhile,a Ni-catalyzed cross-coupling of aryl thioethers with alkyl Grignard reagents has been presented accompanied by the cleavage of the C_(aryl)–SMe bond.An unprecedented three-component domino oxidative coupling of diazocompounds for the efficient synthesis of?-azido-?-amino esters(17%-87%yields)with non-activated dimethylamino compounds and simple TMSN₃ has been achieved using the BI-OH as the oxidant.More importantly,the introduction of the oxazolidinone and camphorsultam as the auxiliary attached to the diazocarbonyl compounds can successfully impart its chirality,leading to corresponding products with an essentially single stereoisomer.Preliminary mechanism studies have shown that the reaction process not only involves free radicals,but also contains imine ions,which is a mixing mechanism.A new method has been introduced for the preparation of alkenyl boronic esters(40%-94%yields),which can make the reaction process mild and efficient(30 min)using alkenyl(aryl)iodonium salts as pre-activated alkene counterparts through the copper-catalyzed cross-coupling.Preliminary mechanism studies have shown that the reaction could be carried out through the oxidative addition-reductive elimination Cu(I)/Cu(?)catalytic cycle.Novel iodobenzene catalysts based on chiral binaphthyl-oxazoline scaffold have been designed and synthesized to explore asymmetric bromo-cyclization reactions.So far,through the preliminary screening of different chiral iodobenzene catalysts,reaction solvents,reaction temperatures and bromine sources,the asymmetric bromolactonization of unsaturated carboxylic acid compound has been achieved with 85% yield and 37% ee.