Brennan J. Crawford, Calum Bochenek, Luis D. Garcia Espinosa, Addie R. Keating, Kayla Williams-Pavlantos, Chrys Wesdemiotis and James M. Eagan*,
{"title":"Anionic Conjugate Addition Oligomerization of Carbon Dioxide/Butadiene Derived Lactones","authors":"Brennan J. Crawford, Calum Bochenek, Luis D. Garcia Espinosa, Addie R. Keating, Kayla Williams-Pavlantos, Chrys Wesdemiotis and James M. Eagan*, ","doi":"10.1021/acsmacrolett.4c00164","DOIUrl":null,"url":null,"abstract":"<p >Nucleophilic and non-nucleophilic bases have been employed in anionic oligomerization of unsaturated δ-valerolactone (3-ethylidene-6-vinyltetrahydro-2<i>H</i>-pyran-2-one) (<b>1</b>). Compared to the seminal findings with 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), the unsaturated lactone reacts with guanidines, disilazanes, and phosphazenes both in bulk and in solution with higher productivities and activities, reaching full conversion with turnover frequencies up to 382 h<sup>–1</sup>. Additionally, reactions using phosphazenes and NaHMDS were active at 1 mol % catalyst loadings both in solvent and in bulk monomer at room temperature. Characterization of the reaction products by <sup>1</sup>H, <sup>13</sup>C, FTIR, MALDI-MS, tandem mass spectrometry (MS/MS), and ion mobility mass spectrometry (IM-MS) revealed microstructural differences dependent on the nucleophilicity of the organocatalytic base and reaction conditions. The products from phosphazene-catalyzed reactions are consistent with selective vinylogous 1,4-conjugate addition, whereas both conjugate addition and ring-opening mechanisms are observed in TBD. DSC reveals that these microstructures can be tuned to have a <i>T</i><sub>g</sub> range between −18 and 80 °C, while SEC and MALDI-MS reveal that only low molar mass oligomers are formed (748–5949 g/mol). From these results, an approach for selectively favoring the vinylogous 1,4-conjugate addition pathway is obtained over ring-opening reactivity.</p>","PeriodicalId":18,"journal":{"name":"ACS Macro Letters","volume":null,"pages":null},"PeriodicalIF":5.1000,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"ACS Macro Letters","FirstCategoryId":"92","ListUrlMain":"https://pubs.acs.org/doi/10.1021/acsmacrolett.4c00164","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"POLYMER SCIENCE","Score":null,"Total":0}
引用次数: 0
Abstract
Nucleophilic and non-nucleophilic bases have been employed in anionic oligomerization of unsaturated δ-valerolactone (3-ethylidene-6-vinyltetrahydro-2H-pyran-2-one) (1). Compared to the seminal findings with 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), the unsaturated lactone reacts with guanidines, disilazanes, and phosphazenes both in bulk and in solution with higher productivities and activities, reaching full conversion with turnover frequencies up to 382 h–1. Additionally, reactions using phosphazenes and NaHMDS were active at 1 mol % catalyst loadings both in solvent and in bulk monomer at room temperature. Characterization of the reaction products by 1H, 13C, FTIR, MALDI-MS, tandem mass spectrometry (MS/MS), and ion mobility mass spectrometry (IM-MS) revealed microstructural differences dependent on the nucleophilicity of the organocatalytic base and reaction conditions. The products from phosphazene-catalyzed reactions are consistent with selective vinylogous 1,4-conjugate addition, whereas both conjugate addition and ring-opening mechanisms are observed in TBD. DSC reveals that these microstructures can be tuned to have a Tg range between −18 and 80 °C, while SEC and MALDI-MS reveal that only low molar mass oligomers are formed (748–5949 g/mol). From these results, an approach for selectively favoring the vinylogous 1,4-conjugate addition pathway is obtained over ring-opening reactivity.
期刊介绍:
ACS Macro Letters publishes research in all areas of contemporary soft matter science in which macromolecules play a key role, including nanotechnology, self-assembly, supramolecular chemistry, biomaterials, energy generation and storage, and renewable/sustainable materials. Submissions to ACS Macro Letters should justify clearly the rapid disclosure of the key elements of the study. The scope of the journal includes high-impact research of broad interest in all areas of polymer science and engineering, including cross-disciplinary research that interfaces with polymer science.
With the launch of ACS Macro Letters, all Communications that were formerly published in Macromolecules and Biomacromolecules will be published as Letters in ACS Macro Letters.