Asymmetric Synthesis of α,α-Disubstituted Amino Acids by Cycloaddition of (<i>E</i>)-Ketonitrones with Vinyl Ethers
作者:Xiaofei Zhang、Pascale Cividino、Jean-François Poisson、Pavlo Shpak-Kraievskyi、Mathieu Y. Laurent、Arnaud Martel、Gilles Dujardin、Sandrine Py
DOI:10.1021/ol500483t
日期:2014.4.4
Original acyclic (E)-α,α-dialkylketonitrones bearing a chiral auxiliary on their nitrogen atom were synthesized and successfully employed for the asymmetric synthesis of α,α-disubstituted amino acids using regio- and stereocontrolled 1,3-dipolar cycloaddition reactions with vinyl ethers. N-Glycosyl chiral auxiliaries were found to provide excellent exo- and π-facial stereocontrol. The obtained enantiopure
合成了在氮原子上带有手性助剂的原始无环(E)-α,α-二烷基酮硝酮,并成功地用于区域和立体控制的1,3-偶极环加成反应与乙烯基的不对称合成α,α-二取代氨基酸醚。发现N-糖基手性助剂可提供优异的exo-和π-面部立体控制。所获得的对映纯环加合物通过中间季酸酐的高度区域选择性开口选择性地转化为功能性α,α-二取代氨基酸和相关的β肽。