Stereo- and regiocontrol in intermolecular [2+2] cycloadditions between diarylketenes and allenamides to access
Akshay Suresh Kshirsagar1, Sayaji Arjun More1, Rai-Shung Liu1
1A Frontier Research Center of Matter Science and Technology, Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan, ROC. rsliu@mx.nthu.edu.tw.
Abstract:
The development of intermolecular [2+2] cycloadditions between allenamides and diarylketenes is described. α-Aryldiazo arylketones are employed as ketene precursors that react smoothly with allenamides in the presence of a P(C6F5)3 promoter. High diastereoselectivity (dr > 20 : 1) with endo-regioselectivity can be achieved when two aryl groups of ketenes have opposite electronic properties. The role of P(C6F5)3 is to increase the reaction yields, but also enhancing stereoselectivity.
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