Milanpreet Kaur , Julian C. Cooper , Jeffrey F. Van Humbeck
{"title":"缺电子杂杂环中苄基 C-H 羟基的位点选择性。","authors":"Milanpreet Kaur , Julian C. Cooper , Jeffrey F. Van Humbeck","doi":"10.1039/d4ob00268g","DOIUrl":null,"url":null,"abstract":"<div><p>Benzylic C–H bonds can be converted into numerous functional groups, often by mechanisms that involve hydrogen atom transfer as the key bond breaking step. The abstracting species is most often an electrophilic radical, which makes these reactions best suited to electron-rich C–H bonds to achieve appropriate polarity matching. Thus, electron deficient systems such as pyridine and pyrimidine are relatively unreactive, and therefore underrepresented in substrate scopes. In this report, we describe a new method for heterobenzylic hydroxylation—essentially an unknown reaction in the case of pyrimidines—that makes use of an iodine(<span>iii</span>) reagent to afford very high selectivity towards electron-deficient azaheterocycles in substrates with more than one reactive position and prevents over-oxidation to carbonyl products. The identification of key reaction byproducts supports a mechanism that involves radical coupling in the bond forming step.</p></div>","PeriodicalId":96,"journal":{"name":"Organic & Biomolecular Chemistry","volume":null,"pages":null},"PeriodicalIF":2.9000,"publicationDate":"2024-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Site-selective benzylic C–H hydroxylation in electron-deficient azaheterocycles†\",\"authors\":\"Milanpreet Kaur , Julian C. Cooper , Jeffrey F. Van Humbeck\",\"doi\":\"10.1039/d4ob00268g\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Benzylic C–H bonds can be converted into numerous functional groups, often by mechanisms that involve hydrogen atom transfer as the key bond breaking step. The abstracting species is most often an electrophilic radical, which makes these reactions best suited to electron-rich C–H bonds to achieve appropriate polarity matching. Thus, electron deficient systems such as pyridine and pyrimidine are relatively unreactive, and therefore underrepresented in substrate scopes. In this report, we describe a new method for heterobenzylic hydroxylation—essentially an unknown reaction in the case of pyrimidines—that makes use of an iodine(<span>iii</span>) reagent to afford very high selectivity towards electron-deficient azaheterocycles in substrates with more than one reactive position and prevents over-oxidation to carbonyl products. The identification of key reaction byproducts supports a mechanism that involves radical coupling in the bond forming step.</p></div>\",\"PeriodicalId\":96,\"journal\":{\"name\":\"Organic & Biomolecular Chemistry\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":2.9000,\"publicationDate\":\"2024-06-19\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Organic & Biomolecular Chemistry\",\"FirstCategoryId\":\"92\",\"ListUrlMain\":\"https://www.sciencedirect.com/org/science/article/pii/S1477052024004944\",\"RegionNum\":3,\"RegionCategory\":\"化学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"CHEMISTRY, ORGANIC\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Organic & Biomolecular Chemistry","FirstCategoryId":"92","ListUrlMain":"https://www.sciencedirect.com/org/science/article/pii/S1477052024004944","RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, ORGANIC","Score":null,"Total":0}
Site-selective benzylic C–H hydroxylation in electron-deficient azaheterocycles†
Benzylic C–H bonds can be converted into numerous functional groups, often by mechanisms that involve hydrogen atom transfer as the key bond breaking step. The abstracting species is most often an electrophilic radical, which makes these reactions best suited to electron-rich C–H bonds to achieve appropriate polarity matching. Thus, electron deficient systems such as pyridine and pyrimidine are relatively unreactive, and therefore underrepresented in substrate scopes. In this report, we describe a new method for heterobenzylic hydroxylation—essentially an unknown reaction in the case of pyrimidines—that makes use of an iodine(iii) reagent to afford very high selectivity towards electron-deficient azaheterocycles in substrates with more than one reactive position and prevents over-oxidation to carbonyl products. The identification of key reaction byproducts supports a mechanism that involves radical coupling in the bond forming step.