{"title":"Desymmetrization of 2-(1,5-Dialkoxypent-3-yl)phenyl Grignard Reagents by Rhodium-Catalyzed Asymmetric 1,4-Shift/β-Alkoxy Elimination","authors":"Yu-Hsuan Tsai, Yi-Hsuan Chen, Ting-Wei Sun, Sing-Wei Chen, Hsyueh-Liang Wu* and Tamio Hayashi*, ","doi":"10.1021/acscatal.4c02879","DOIUrl":null,"url":null,"abstract":"<p >The Grignard reagents generated from 2-(1,5-dialkoxypent-3-yl)aryl bromides were treated with a chiral rhodium catalyst with either a segphos or binap ligand to give high yields of 3-aryl-5-alkoxy-1-pentenes with high enantioselectivity (up to 99% ee). Based on deuterium labeling studies, it is proposed that the catalytic cycle consists of (1) transmetalation of the Grignard reagent to a RO-Rh catalyst generating an aryl-Rh intermediate, (2) a 1,4-shift of Rh from aromatic carbon to one of the two homobenzylic carbons, which is not an enantioselectivity-determining step, (3) migration of Rh to a β-alkoxyalkyl position ready for selective β-alkoxy elimination through a sequence of β-hydrogen elimination/hydrorhodations, and (4) β-alkoxy elimination resulting in the formation of an enantioenriched elimination product.</p>","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":null,"pages":null},"PeriodicalIF":11.3000,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acscatal.4c02879","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"ACS Catalysis ","FirstCategoryId":"92","ListUrlMain":"https://pubs.acs.org/doi/10.1021/acscatal.4c02879","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
Abstract
The Grignard reagents generated from 2-(1,5-dialkoxypent-3-yl)aryl bromides were treated with a chiral rhodium catalyst with either a segphos or binap ligand to give high yields of 3-aryl-5-alkoxy-1-pentenes with high enantioselectivity (up to 99% ee). Based on deuterium labeling studies, it is proposed that the catalytic cycle consists of (1) transmetalation of the Grignard reagent to a RO-Rh catalyst generating an aryl-Rh intermediate, (2) a 1,4-shift of Rh from aromatic carbon to one of the two homobenzylic carbons, which is not an enantioselectivity-determining step, (3) migration of Rh to a β-alkoxyalkyl position ready for selective β-alkoxy elimination through a sequence of β-hydrogen elimination/hydrorhodations, and (4) β-alkoxy elimination resulting in the formation of an enantioenriched elimination product.
期刊介绍：
ACS Catalysis is an esteemed journal that publishes original research in the fields of heterogeneous catalysis, molecular catalysis, and biocatalysis. It offers broad coverage across diverse areas such as life sciences, organometallics and synthesis, photochemistry and electrochemistry, drug discovery and synthesis, materials science, environmental protection, polymer discovery and synthesis, and energy and fuels.
The scope of the journal is to showcase innovative work in various aspects of catalysis. This includes new reactions and novel synthetic approaches utilizing known catalysts, the discovery or modification of new catalysts, elucidation of catalytic mechanisms through cutting-edge investigations, practical enhancements of existing processes, as well as conceptual advances in the field. Contributions to ACS Catalysis can encompass both experimental and theoretical research focused on catalytic molecules, macromolecules, and materials that exhibit catalytic turnover.
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