Expedited Synthesis of Axially Chiral 3-Monosilyl and 3,3′-Bis-silyl Biphenols, Binaphthols, and Phosphoramidites Enabled by Catalytic Two-Fold C–H Silylation with a Traceless Acetal Directing Group
Year: 2024
Type: article
Abstract: The design and development of supporting ligands have significantly propelled the discovery of new catalytic reactions and the improvement of existing ones. Among these, axially chiral biphenols and 1,1'-binaphthalene-2,2'-diol (BINOL) are some of the most privileged ligands used in a wide array of enantioselective reactions. Despite the well-established benefits of structural modifications to biphenol and BINOL scaffolds, particularly at their 3,3'-positions-for enhancing reactivity and stereofidelity in catalytic asymmetric transformations-only a limited number of 3,3'-bis-functionalized biphenols and BINOLs are currently available. Here, we report a unified strategy to rapidly access a range of axially chiral 3-monosilyl and 3,3' bis-silyl-substituted and biphenols and BINOLs as well as their corresponding 3-monosilyl and 3,3' bis-silyl BINOL-based phosphoramidites. This approach involves traceless acetal-directed, catalytic two-fold C-H silylation of axially chiral biaryls, coupled with selective monoprotodesilylation, expanding the versatility of catalytic C-H functionalization in ligand design and development. Scope studies on the augmentation of the topological space of potentially stereoselectivity-amplifying 3,3'-bis-silyl substituents in axially chiral biphenols and BINOLs were achieved through C-H silylation of biphenols and BINOLs using various dihydrosilanes, as well as the derivatization of 3,3'-silanes, leading to functionalized silane-substituted biphenols and BINOLs. Lastly, the phosphoramidation of newly synthesized 3-monosilyl and 3,3' bis-silyl BINOL and biphenols with dichlorophosphinamine provided a series of 3-monosilyl and 3,3' bis-silyl BINOL-based phosphoramidites. The efficiency of this synthetic approach is underscored by its short synthetic steps, expedited reaction times, and minimal purification, making it versatile for the synthesis of a wide array of organosilicon-functionalized axially chiral biaryls and phosphoramidites.
Source: ACS Catalysis
Authors: Hiep H. Nguyen, Suman Das Adhikary, Yao Chung Chang, Peter Zotor, Junha Jeon
Institution: The University of Texas at Arlington
Language: English
Subfield: Organic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
Awards: G1179245369, G1191611765, G1559871863, Collaborative Research: Hydrogen Atom Transfer Lewis Base Catalysis, G2132361153, Upgrade of a 300 MHz NMR Spectrometer for Teaching and Research, G4447068223, G5247440779, G5648807998, G621799218, Upgrade of NMR Facilities for Research and Teaching, G8591701175, G9000054717
OpenAlex ID: W4405963253