An Ultimate Stereocontrol in Asymmetric Synthesis of Optically Pure Fully Aromatic Helicenes

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• 作者：Michal 艩谩mal ; Serghei Chercheja ; Ji艡铆 Ryb谩膷ek ; Jana Vacek Chocholou拧ov谩 ; Jaroslav Vacek ; Lucie Bedn谩rov谩 ; David 艩aman ; Irena G. Star谩 ; Ivo Star媒
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：July 8, 2015
• 年：2015
• 卷：137
• 期：26
• 页码：8469-8474
• 全文大小：533K
• ISSN：1520-5126

文摘

The role of the helicity of small molecules in enantioselective catalysis, molecular recognition, self-assembly, material science, biology, and nanoscience is much less understood than that of point-, axial-, or planar-chiral molecules. To uncover the envisaged potential of helically chiral polyaromatics represented by iconic helicenes, their availability in an optically pure form through asymmetric synthesis is urgently needed. We provide a solution to this problem present since the birth of helicene chemistry in 1956 by developing a general synthetic methodology for the preparation of uniformly enantiopure fully aromatic [5]-, [6]-, and [7]helicenes and their functionalized derivatives. [2 + 2 + 2] Cycloisomerization of chiral triynes combined with asymmetric transformation of the first kind (ultimately controlled by the 1,3-allylic-type strain) is central to this endeavor. The point-to-helical chirality transfer utilizing a traceless chiral auxiliary features a remarkable resistance to diverse structural perturbations.