Mechanistic insights into annulation of arylidene- [Delta] [sup] 2-pyrrolin-4-ones by cinchona squaramide-based organocatalysts

Ciber, Luka (author), Ričko, Sebastijan (author), Gregorc, Jure (author), Požgan, Franc (author), Svete, Jurij (author), Brodnik, Helena (author), Štefane, Bogdan (author), Grošelj, Uroš (author)

Arylidene-Δ2-pyrrolin-4-ones undergo organocatalyzed annulation with malononitrile, furnishing dihydropyrano[3,2-b]pyrroles (18 examples, 0–77% ee in dichloromethane, 11–44% ee in methanol). The products could be enantiomerically enriched by trituration (11 examples, 95–99% ee). Enantioselectivity was dependent on the nature of the substrate and the conformation of the catalyst, which in turn was solvent-controlled. The reaction mechanism, which included two pseudo-enantiomeric organocatalyst conformations, was investigated by experimental and quantum chemical methods. The reaction mechanism consists of Michael addition reaction step followed by 6-exo-dig annulation, which was found to be the rate determining step. Additionally, it was identified that the preferred reaction pathway follows the model originally proposed by Pápai et al.

• Language: English
• Keywords: organocatalysis, asymmetric synthesis, enantioselectivity, solvent effects, pyrrolone, pseudo-enantiomeric catalyst conformations
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Publication status: In print
• Publication version: Author Accepted Manuscript
• Year: 2022
• Number of pages: Str. 1-14
• Numbering: Vol. 464, iss.
• PID: 20.500.12556/RUL-134970
• UDC: 547.74:544.47
• ISSN on article: 1615-4150
• DOI: 10.1002/adsc.202101369
• COBISS.SI-ID: 97278211
• Publication date in RUL: 15.02.2022

Record is a part of a journal

• Title: Advanced synthesis & catalysis
• Publisher: Wiley
• ISSN: 1615-4150
• COBISS.SI-ID: 22726149

Licences

• License: CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
• Link: http://creativecommons.org/licenses/by-nc-nd/4.0/
• Description: The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.
• Licensing start date: 14.01.2022

Secondary language

• Language: Slovenian
• Keywords: organokataliza, asimetrična sinteza, enantioselektivnost, učinki topil, piroloni, psevdo-enantiomerne konformacije katalizatorja

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P1-0179
• Name: Napredna organska sinteza in kataliza