Katharina Röser, Lucas Prameshuber, Sajid Jahangir, Sharath Chandra Mallojjala, Jennifer S. Hirschi, Mario Waser
We herein report a protocol for the asymmetric 1,4-addition of hydantoins to various Michael acceptors by utilizing Cinchona alkaloid-based chiral quaternary ammonium salt catalysts. Various products were obtained with moderate to good enantioselectivities and accompanying computational investigations helped to identify key interactions responsible for the observed selectivity. DFT calculations along with non-covalent interaction plots reveal the presence of numerous stabilizing non-classical hydrogen bonding interactions along with other non-covalent interactions between the chiral quaternary ammonium salt and hydantoin molecule in the C−C bond forming transition states leading to the formation of the products. In addition, a first proof-of-concept for an analogous a-sulfanylation reaction, albeit with poor selectivity, is reported as well.
{"title":"Chiral Quaternary Ammonium Salt-Catalyzed Enantioselective Addition Reactions of Hydantoins","authors":"Katharina Röser, Lucas Prameshuber, Sajid Jahangir, Sharath Chandra Mallojjala, Jennifer S. Hirschi, Mario Waser","doi":"10.1002/hlca.202300234","DOIUrl":"10.1002/hlca.202300234","url":null,"abstract":"<p>We herein report a protocol for the asymmetric 1,4-addition of hydantoins to various Michael acceptors by utilizing Cinchona alkaloid-based chiral quaternary ammonium salt catalysts. Various products were obtained with moderate to good enantioselectivities and accompanying computational investigations helped to identify key interactions responsible for the observed selectivity. DFT calculations along with non-covalent interaction plots reveal the presence of numerous stabilizing non-classical hydrogen bonding interactions along with other non-covalent interactions between the chiral quaternary ammonium salt and hydantoin molecule in the C−C bond forming transition states leading to the formation of the products. In addition, a first proof-of-concept for an analogous a-sulfanylation reaction, albeit with poor selectivity, is reported as well.</p>","PeriodicalId":12842,"journal":{"name":"Helvetica Chimica Acta","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/hlca.202300234","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139065626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This review describes applications of radical reactions developed in the authors’ laboratory for the modification of carbohydrates. It focuses on tin-free variation on the Barton-McCombie deoxygenation; on reductive de-iodination; on intermolecular radical additions of xanthates; on allylations and vinylations of xanthates and iodides, with emphasis on allylations using allylic alcohols activated as fluoropyridyl ethers; and, finally, on the synthesis of mercaptosugars.
{"title":"Radicals and Carbohydrates: A Grand Alliance","authors":"Béatrice Quiclet-Sire, Samir Z. Zard","doi":"10.1002/hlca.202300218","DOIUrl":"10.1002/hlca.202300218","url":null,"abstract":"<p>This review describes applications of radical reactions developed in the authors’ laboratory for the modification of carbohydrates. It focuses on tin-free variation on the Barton-McCombie deoxygenation; on reductive de-iodination; on intermolecular radical additions of xanthates; on allylations and vinylations of xanthates and iodides, with emphasis on allylations using allylic alcohols activated as fluoropyridyl ethers; and, finally, on the synthesis of mercaptosugars.</p>","PeriodicalId":12842,"journal":{"name":"Helvetica Chimica Acta","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2023-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138825643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}