The Studies On (Diacetoxyiodo)Benzene-Mediated Oxidation Reaction Of Ethynylcarbinols And Direct Sp~3 C—H Bond Functionalization

(Diacetoxyiodo)benzene has been utilized as one of the most widely useful hypervalent iodine reagents in organic synthesis. (Diacetoxyiodo)benzene was mainly applied in the selective oxidation of alcohols, phenols, unsaturated alkene or alkyne compounds, the oxidative coupling of electron-rich aromatic rings, the activation of C-H bond and the radical cyclization reaction. They attracted much attention of chemists and pharmacologists due to their easy applicationin synthesis of multi-hydroxy functional groups containing biological and pharmacological activities, which played a very important role in the synthetic methodology.This thesis mainly focused on a new efficient cascade process that has been identified for the preparation of α,α’-diacetoxy ketones or glycerol derivatives from propargyl alcohols oxidatived by PhI(OAc)2 in HOAc solvent. The PhI(OAc)2--Mediated sp3 C-H functionalization of 1,1-disubstituted ethynols in HOAc to afford β-acetoxy alcohols was also developed. This thesis could be divided into the following two parts:In the first part, we studied the oxidation of various types of propargyl alcohols by PhI(OAc)2 in HOAc to afford 14 examples of a,a’-diacetoxy ketones and 12 of them were new compounds. The effects of different solvents, temperature and the amount of oxidant were screened. Detailed mechanistic studies revealed that the Ortho-OH group might go through a Michael addition type attacking to the hypervalent iodinium salts intermediate intra-molecularly, namely, the OH group might act as an intra-molecular nucleophile. What’s more, this method was successfully applied to modify the (-)-Norgestrel into a,a’-diacetoxy ketones. Three examples of glycerol derivatives were easily synthesized by one pot reaction:the oxidation of propargyl alcohols and the following remove of solvent gave the intermediates without column chromatography purification. Subsequently, the direct reduction with NaBHU provided the desired products.In the second part, we investigated the sp3 C-H functionalization of various 1,1-disubstituted ethanol mediated by PhI(OAc)2 in HO Ac to give 9 examples of β-acetoxy alcohols. The effect of different solvents, temperature and the amount of oxidant were studied. Products of the acetoxylation could be obtained only when the HOAc was used as the solvent. The scope of the sp3 C-H functionalization of various 1,1-disubstituted ethanol substrates was broad, which laid the foundation for its transformation into more useful intermediates.