Supramolecular diversity of oxabicyclo[2.2.2]octenes formed between substituted 2H-pyran-2-ones and vinyl-moiety-containing dienophiles

Kranjc, Krištof (author), Juranovič, Amadej (author), Kočevar, Marijan (author), Perdih, Franc (author)

In Diels–Alder reactions, 2H-pyran-2-ones as dienes can yield a large variety of cycloadducts with up to four contiguous carbon stereogenic centers. Some of the potentially most useful, however difficult to prepare due to their low thermal stability, are the primary CO$_2$-containing oxabicyclo[2.2.2]octenes, which could be formed as eight distinctive isomers (two sets of regioisomers, each of these composed of four different stereoisomers). A high-pressure synthesis of such products was recently described in a few cases where vinyl-moiety-containing dienophiles were used as synthetic equivalents of acetylene. However, structures of the primary products have been so far only rarely investigated in detail. Herein, we present seven novel single-crystal X-ray diffraction structures of such cycloadducts of both stereoisomeric forms, i.e., endo and exo. Additionally, we present a single-crystal structure of a rare case of a cyclohexadiene system stable at room temperature, obtained as a secondary product upon the retro-hetero-Diels–Alder elimination of CO$_2$ under thermal conditions (microwave irradiation), during this elimination the symmetry is increased and out of eight initially possible isomers of the reactant, this number in the product is decreased to four. In oxabicyclo[2.2.2]octene compounds, centrosymmetric hydrogen bonding was found to be the predominant motif and diverse supramolecular patterns were observed due to rich variety of C–H· · · O and C–H· · · π interactions.

• Language: English
• Keywords: Diels-Alder reaction, organic synthesis, heterocycles, hydrogen bonds, crystal structure, X-ray diffraction, high-pressure conditions, microwave-assisted reactions, aggregation, crystal architecture
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Publication status: Published
• Publication version: Version of Record
• Year: 2020
• Number of pages: 23 str.
• Numbering: Vol. 12, iss. 10, art. 1714
• PID: 20.500.12556/RUL-134710
• UDC: 547.81:547.72
• ISSN on article: 2073-8994
• DOI: 10.3390/sym12101714
• COBISS.SI-ID: 33257219
• Publication date in RUL: 27.01.2022

Record is a part of a journal

• Title: Symmetry
• Shortened title: Symmetry
• Publisher: Molecular Diversity Preservation International
• ISSN: 2073-8994
• COBISS.SI-ID: 517592345

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.
• Licensing start date: 17.10.2020

Secondary language

• Language: Slovenian
• Keywords: Diels-Alderjeva reakcija, organska sinteza, heterocikli, vodikova vez, kristalna struktura

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P1-0230
• Name: Organska kemija: sinteza, struktura in aplikacija

• Funder: ARRS - Slovenian Research Agency
• Project number: P1-0175
• Name: Napredna anorganska kemija