Studies On The Regio-and Stereo Selective Synthesis Of Polysubstituted Alkenyl Ethers

Alkenyl ethers are important building blocks in organic chemistry. However, there are only limited methods for the concise synthesis of these motifs. Herein, several protocols for the regio-and stereoselective access of enol ethers have been realized featuring the regioselective hydroboration or carbopalladation of ynol ethers. The dissertation consists of two parts:Firstly, a highly efficient and practical method for the synthesis of β,β-disubstituted vinyl ethers has been realized by a tandem hydroboration/Suzuki-Miyaura coupling of ynol ethers. The reaction proceeds under mild reaction conditions and tolerates a wide range of functional groups. Moreover, it offers an effective access to the labile diaryl acetaldehydes by the hydrolysis of β,β-disubstituted vinyl ethers in the presence of TFA.Then, a Pd-catalyzed reductive addition of organohalides, including aryl, alkenyl, and benzyl halides, to ynol ethers has been achieved, giving a,β-and β,β-disubstituted olefinic ethers in satisfactory yields with excellent regio-and stereoselectivity, which employs the readily available2-propanol as the hydride source. The regioselectivity of this reaction is found to be determined by the choice of organohalide components. The reversed regioselectivity of the hydrobenzylation as compared to hydroarylation or hydroakenylation reaction may be attributed to the electrophilic properties of benzylpalladium complexes. Further investigations on the illustration of switch of the regiochemistry are currently undergoing in this group.Clearly, the above methods provide new effective approaches to the stereodefined polysubstituted enol ethers, and we believe that they will be of value for organic synthesis.