Stereocontrolled Cyanohydrin Ether Synthesis through Chiral Br酶nsted Acid-Mediated Vinyl Ether Hydrocyanation

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• 作者：Chunliang Lu ; Xiaoge Su ; Paul E. Floreancig
• 刊名：Journal of Organic Chemistry
• 出版年：2013
• 出版时间：September 20, 2013
• 年：2013
• 卷：78
• 期：18
• 页码：9366-9376
• 全文大小：541K
• 年卷期：v.78,no.18(September 20, 2013)
• ISSN：1520-6904

文摘

Vinyl ethers can be protonated to generate oxocarbenium ions that react with Me<sub>3sub>SiCN to form cyanohydrin alkyl ethers. Reactions that form racemic products proceed efficiently upon conversion of the vinyl ether to an 伪-chloro ether prior to cyanide addition in a pathway that proceeds through Br酶nsted acid-mediated chloride ionization. Enantiomerically enriched products can be accessed by directly protonating the vinyl ether with a chiral Br酶nsted acid to form a chiral ion pair. Me<sub>3sub>SiCN acts as the nucleophile and PhOH serves as a stoichiometric proton source in a rare example of asymmetric bimolecular nucleophilic addition into an oxocarbenium ion. Computational studies have provided a model for the interaction between the catalyst and the oxocarbenium ion.