Atroposelective Synthesis of Triaryl α‐Pyranones with 1, 2‐Diaxes by N‐Heterocyclic Carbene Organocatalysis. (23rd November 2022)

• Record Type: Journal Article
• Authors: Zhang, Simiao; Wang, Xiaoxue; Han, Li‐Li; Li, Jibin; Liang, Zheng; Wei, Donghui; Du, Ding
• Is Part Of: Angewandte Chemie. Volume 134:Number 52(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-11-23
• Subjects: Atroposelectivity -- N-Heterocyclic Carbenes -- Organocatalysis -- Reaction Mechanisms -- Synthetic Methods; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.202212005
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: Atropisomers bearing multiple stereogenic axes are of increasing importance to the field of material science, pharmaceuticals, and catalysis. However, the atroposelective construction of multi‐axis atropisomers remains rare and challenging, due to the intrinsical difficulties in the stereo‐control of the multiple stereogenic axes. Herein, we demonstrate a single‐step construction of a new class of 1, 2‐diaxially chiral triaryl α‐pyranones by an N‐heterocyclic carbene organocatalytic asymmetric [3+3] annulation of well‐designed alkynyl acylazolium precursors and enolizable sterically hindered 2‐aryl ketones. The protocol features broad substrate scope (>50 examples), excellent stereo‐control (most cases >20 : 1 dr, up to 99.5 : 0.5 er), and potentially useful synthetic applications. The success of this reaction relies on the rational design of structurally matched reaction partners and the careful selection of the asymmetric catalytic system. DFT calculations have also been performed to discover and rationalize the origin of the high stereoselectivity of this reaction. Abstract : The single‐step atroposelective construction of triaryl α‐pyranones with stereogenic 1, 2‐diaxes was accomplished by NHC organocatalysis. The structure of the substrates and the catalytic system play a critical role in the success of this protocol. DFT calculations were performed to rationalize the origin of the high stereoselectivity.