The Research Of Desulfitative Addition Reactions And Multi-substituted Oxazoles Preparation

The C-C and C-heteroatom bond formation is one of the most exciting researchtopics in organic chemistry. Over the past few years, various efficient syntheticmethodologies of new C-C and C-heteroatom bonds have been developed. Amongthem, the transition metal-catalyzed cross-coupling (Kumada, Stille, Negishi,Suzuki-Miyaura, Hiyama), Tsuji-Trost allylation, and Buchwald-Hartwig aminationreactions are particularly valuable tools. This article presents several C-C andC-heteroatom bond-forming reactions via C-H functionalization. Detailed researchwas described as follows:1. This thesis mainly focused on developing new method of C-C bond formationusing arenesulfinic acid sodium salts and α,β-unsaturated ketones as starting materials.We found that arenesulfinic acid sodium salts can added with α,β-unsaturatedcompounds for the nucleophilicity after desulfitative. Unlike the decarboxylativecoupling reaction, no electron-withdrawing or donating group ortho to the sulfinicacid group was necessary to ensure the desulfitative addition. The reaction can beperformed smoothly with a wide variety of functionalities, mild reaction conditionsand highly selectivity.2. A research of palladium-catalyzed desulfitative-denitrogenative conjugateaddition of arylsulfonyl hydrazides to α,β-unsaturated ketones was reported. Variousarylsulfonyl hydrazides with or without substituents selectively added withα,β-unsaturated ketones and selectively afforded the products in high yields. In mostcases, molecular oxygen can act efficiently as the sole oxidant.3. A novel approach for the synthesis of multi-substituted oxazoles using CuBras the catalyst has been developed. Readily available β-diketones and primaryarylamides were used as the starting materials.4-Methyl substituted oxazoles wereobtained as the major products when unsymmetrical β-diketones were used as thecoupling partners. This strategy affords an efficient approach for the synthesis ofmulti-substituted oxazoles from readily available starting materials with cheap andlow toxic copper catalyst.