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Updated: Aug 29, 2025

Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
Published on: September 18, 2016
A Metal-Free and Redox-Neutral Benzylic C-O Cyclization for Succinct Access of Helical Chromenes
Tianyi Liu1,2, Kin Boon Gan1,2, Rong-Lin Zhong1,3
1State Key Laboratory of Synthetic Chemistry and Department of Chemistry, The Chinese University of Hong Kong, New Territories, Hong Kong, China.
Abstract:
A redox-neutral benzylic C-O cyclization under beneficial transition-metal-free conditions is reported. Key to the success of this process is the utilization of the Tf anion as the leaving group for achieving the redox-neutral transformation. This protocol delivers a series of captivating helical compounds having various functionality in good-to-excellent yields. It is particularly noteworthy that sterically hindered helical compounds are conformationally stable. In addition to simple helical chromenes, the bihelical multiple-ring systems which are potentially useful in material chemistry are also easily attained by employing this method. DFT calculation revealed that quinone intermediate is the key species, among four possible mechanisms, for accomplishing the desired cyclization via an oxa-6π-electrocyclization pathway.
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