The Morita-Baylis-Hillman-Type [3,3]-rearrangement Of Aryl Iodanes With α,β-unsaturated Oxazolines

[3,3]-Sigmatropic rearrangement is a powerful process in organic synthesis.In the past few years,the [3,3]-σ-rearrangement of aryl iodanes has attracted increasing attentions.Unlike classic Claisen rearrangement,this iodonio-Claisen rearrangement can be implemented by simply mixing aryl iodanes with certain nucleophilies leading to ortho C-H functionalized aryl iodides.Importantly,the remaining iodine atom provides a versatile platform for further elaboration of products.On the basis of literature analysis and previous research experience,we found that the key to the success of the rearrangement reaction is the construction of the rearrangement precursors.Different from the previous "assembly" strategy,in this thesis,we describe a new strategy namely the “assembly/addition” for triggering the rearrangement of aryl iodanes with α,β-unsaturated oxazolines.Specifically,TMSOTf initiates the electrophilic assembly of both coupling partners,providing an unstable α,β-unsaturated imine iodonium intermediate.The subsequent Morita-Baylis-Hillman(MBH)-type addition forms a ketenimine iodonium species that can readily undergo [3,3]-σ-rearrangement and β-elimination to α-arylated α,β-unsaturated oxazolines.The Morita-Baylis-Hillman-type [3,3]-σ-rearrangement of aryl iodanes with α,β-unsaturatedoxazolines can proceed at-78 °C.In addition to the excellent chemoand regioselectivity,the reaction showed a remarkable stereoselectivity.In summary,we have developed a new method for the synthesis of α-arylated α,β-unsaturated carbonyl compounds through [3,3]-σ-rearrangement.The new strategy is expected to trigger the development of aromatic [3,3]-σ-rearrangement reactions.