Lin-Yan Bao, Jian-Sen Wang, Lu Li, Rong-Lin Zhong, Zhong-Min Su
{"title":"Theoretical Insight into the Multiple Roles of the Silyl-Phenanthroline Ligand in Ir-Catalyzed C(sp3)–H Borylation","authors":"Lin-Yan Bao, Jian-Sen Wang, Lu Li, Rong-Lin Zhong, Zhong-Min Su","doi":"10.1021/acs.joc.4c01779","DOIUrl":null,"url":null,"abstract":"Silyl-phenanthroline (NN′Si) ligand ancillary iridium-catalyzed C(sp<sup>3</sup>)–H borylation is investigated theoretically. Density functional theory calculations clearly disclose that the (NN′Si)Ir<sup>V</sup>(H)(Bpin)<sub>3</sub> (NN′Si = 6-[(di-<i>tert</i>-butylsilyl)methyl]-1,10-phenanthroline) complex is a resting state, and the (NN′Si)Ir<sup>III</sup>(Bpin)<sub>2</sub> complex serves as an active species in the catalytic cycle. The remarkably high activity of this type of a catalyst arises from the rapid reductive elimination of HBpin from (NN′Si)Ir<sup>V</sup>(H)(Bpin)<sub>3</sub> to generate the active species (NN′Si)Ir<sup>III</sup>(Bpin)<sub>2</sub>. The silyl group plays a crucial role in accelerating the crucial hydride-migration elementary step, which allows the isomerization of the (NN′Si)Ir<sup>V</sup>(R)(H)(Bpin)<sub>2</sub> intermediate to achieve the C(sp<sup>3</sup>)–B reductive elimination and afford the borylated product. Although C(sp<sup>3</sup>)–H borylation with HBpin is thermodynamically unfavorable, the Ir-dihydride intermediate (NN′Si)Ir<sup>V</sup>(H)<sub>2</sub>(Bpin)<sub>2</sub> generated after product formation is slightly more stable than resting-state (NN′Si)Ir<sup>V</sup>(H)(Bpin)<sub>3</sub> in this catalytic cycle, which is an important driving force for the HBpin reaction. Such success was not attained by many other traditional bidentate ligands. The unique regioselectivity of <i>n</i>-butyl ethyl ether and 2-methylheptane, induced by the NN′Si-pincer ligand, is well reproduced and the underlying reason for the selectivity is clearly elucidated.","PeriodicalId":57,"journal":{"name":"Journal of Organic Chemistry","volume":"8 1","pages":""},"PeriodicalIF":3.3000,"publicationDate":"2024-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Organic Chemistry","FirstCategoryId":"1","ListUrlMain":"https://doi.org/10.1021/acs.joc.4c01779","RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, ORGANIC","Score":null,"Total":0}
引用次数: 0
Abstract
Silyl-phenanthroline (NN′Si) ligand ancillary iridium-catalyzed C(sp3)–H borylation is investigated theoretically. Density functional theory calculations clearly disclose that the (NN′Si)IrV(H)(Bpin)3 (NN′Si = 6-[(di-tert-butylsilyl)methyl]-1,10-phenanthroline) complex is a resting state, and the (NN′Si)IrIII(Bpin)2 complex serves as an active species in the catalytic cycle. The remarkably high activity of this type of a catalyst arises from the rapid reductive elimination of HBpin from (NN′Si)IrV(H)(Bpin)3 to generate the active species (NN′Si)IrIII(Bpin)2. The silyl group plays a crucial role in accelerating the crucial hydride-migration elementary step, which allows the isomerization of the (NN′Si)IrV(R)(H)(Bpin)2 intermediate to achieve the C(sp3)–B reductive elimination and afford the borylated product. Although C(sp3)–H borylation with HBpin is thermodynamically unfavorable, the Ir-dihydride intermediate (NN′Si)IrV(H)2(Bpin)2 generated after product formation is slightly more stable than resting-state (NN′Si)IrV(H)(Bpin)3 in this catalytic cycle, which is an important driving force for the HBpin reaction. Such success was not attained by many other traditional bidentate ligands. The unique regioselectivity of n-butyl ethyl ether and 2-methylheptane, induced by the NN′Si-pincer ligand, is well reproduced and the underlying reason for the selectivity is clearly elucidated.
期刊介绍:
Journal of Organic Chemistry welcomes original contributions of fundamental research in all branches of the theory and practice of organic chemistry. In selecting manuscripts for publication, the editors place emphasis on the quality and novelty of the work, as well as the breadth of interest to the organic chemistry community.