Manali A. Mohite, Sonu Sheokand, Maravanji S. Balakrishna
{"title":"Nickel–PNN catalysed sustainable synthesis of polysubstituted quinolines under microwave irradiation","authors":"Manali A. Mohite, Sonu Sheokand, Maravanji S. Balakrishna","doi":"10.1039/d4cy00863d","DOIUrl":null,"url":null,"abstract":"In this manuscript, the synthesis of a series of cationic Ni<small><sup>II</sup></small> complexes based on mixed donor triazolyl-pyridine-based aminophosphine, [(NiCl){<small><sup>R′</sup></small>P<small><sup>R</sup></small>NN}-κ<small><sup>3</sup></small>-P,N,N]OTf (R = H or Me; R′ = Ph or <small><sup><em>t</em></sup></small>Bu), is described. The neutral dearomatized complexes [(NiCl){<small><sup>R′</sup></small>PNN}-κ<small><sup>3</sup></small>-P,N,N] (R′ = Ph or <small><sup><em>t</em></sup></small>Bu) were prepared by deprotonation of [(NiCl){P<small><sup>Ph</sup></small>N(H)N}-κ<small><sup>3</sup></small>-P,N,N]OTf (<strong>Ni1</strong>) and [(NiCl){(<small><sup><em>t</em></sup></small>Bu<small><sub>2</sub></small>P)N(H)N}-κ<small><sup>3</sup></small>-P,N,N]OTf (<strong>Ni3</strong>) with 1 equiv. of <small><sup><em>t</em></sup></small>BuOK. These complexes (0.5 mol%) were employed for the synthesis of substituted quinolines at 110 °C under microwave irradiation with 20 mol% of KOH. Among these, complexes [(NiCl){<small><sup><em>t</em>Bu</sup></small>P<small><sup>H</sup></small>NN-κ<small><sup>3</sup></small>-P,N,N}]OTf (<strong>Ni3</strong>) and [(NiCl){<small><sup><em>t</em>Bu</sup></small>PNN}-κ<small><sup>3</sup></small>-P,N,N] (<strong>Ni5</strong>) were found to be highly efficient. A wide range of derivatives, including aryl, aliphatic, acyclic ketones, primary alcohols and aminobenzyl alcohols, yielded the corresponding quinolines in good to excellent yields (62 examples). A series of control experiments were carried out to establish the reaction mechanism. HR-MS spectral studies were investigated to characterize the nickel-hydride intermediate. Mechanistic studies confirmed that the reaction takes an acceptorless dehydrogenative coupling pathway.","PeriodicalId":66,"journal":{"name":"Catalysis Science & Technology","volume":null,"pages":null},"PeriodicalIF":4.4000,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Catalysis Science & Technology","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1039/d4cy00863d","RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
Abstract
In this manuscript, the synthesis of a series of cationic NiII complexes based on mixed donor triazolyl-pyridine-based aminophosphine, [(NiCl){R′PRNN}-κ3-P,N,N]OTf (R = H or Me; R′ = Ph or tBu), is described. The neutral dearomatized complexes [(NiCl){R′PNN}-κ3-P,N,N] (R′ = Ph or tBu) were prepared by deprotonation of [(NiCl){PPhN(H)N}-κ3-P,N,N]OTf (Ni1) and [(NiCl){(tBu2P)N(H)N}-κ3-P,N,N]OTf (Ni3) with 1 equiv. of tBuOK. These complexes (0.5 mol%) were employed for the synthesis of substituted quinolines at 110 °C under microwave irradiation with 20 mol% of KOH. Among these, complexes [(NiCl){tBuPHNN-κ3-P,N,N}]OTf (Ni3) and [(NiCl){tBuPNN}-κ3-P,N,N] (Ni5) were found to be highly efficient. A wide range of derivatives, including aryl, aliphatic, acyclic ketones, primary alcohols and aminobenzyl alcohols, yielded the corresponding quinolines in good to excellent yields (62 examples). A series of control experiments were carried out to establish the reaction mechanism. HR-MS spectral studies were investigated to characterize the nickel-hydride intermediate. Mechanistic studies confirmed that the reaction takes an acceptorless dehydrogenative coupling pathway.
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