Synlett 2023; 34(19): 2323-2328
DOI: 10.1055/a-2158-7980
letter

DBU-Mediated Dimerization: Facile Access to 9,9′-Bifluorenylidenes and Isoindigos

Authors

  • Nitchakan Purahong

    a   Department of Chemistry and Advanced Pure and Applied Chemistry Research Unit (APAC), School of Science, King Mongkut’s Institute of Technology Ladkrabang, Chalongkrung Road, Ladkrabang District, Bangkok 10520, Thailand
  • Sakchai Hongthong

    b   Division of Chemistry, Faculty of Science and Technology, Rajabhat Rajanagarindra University, Chachoengsao 24000, Thailand
  • Nawasit Chotsaeng

    a   Department of Chemistry and Advanced Pure and Applied Chemistry Research Unit (APAC), School of Science, King Mongkut’s Institute of Technology Ladkrabang, Chalongkrung Road, Ladkrabang District, Bangkok 10520, Thailand
  • Chutima Kuhakarn

    c   Department of Chemistry and Center of Excellence for Innovation in Chemistry (PERCH-CIC), Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand
  • Jatuporn Meesin

    a   Department of Chemistry and Advanced Pure and Applied Chemistry Research Unit (APAC), School of Science, King Mongkut’s Institute of Technology Ladkrabang, Chalongkrung Road, Ladkrabang District, Bangkok 10520, Thailand

This research by King Mongkut’s Institute of Technology Ladkrabang (KMITL) received funding support from the National Science, Research and Innovation Fund (NSRF), Thailand (FRB660065/0258-REKRIS/FF66/21). C.K. thanks the Center of Excellence for Innovation in Chemistry (PERCH-CIC), Ministry of Higher Education, Science, Research and Innovation.


Graphical Abstract

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Abstract

The present work describes the 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-promoted self-dimerization of 9-chlorofluorenes and 3-chlorooxindoles for the preparation of the corresponding 9,9′-bifluorenylidene and isoindigo derivatives in moderate to good yields of 29–97%. The reactions proceed readily in a short reaction time under mild and metal-free conditions. Scale-up syntheses (5.0 mmol) of selected 9,9′-bifluorenylidene derivatives proceed in decent yields, highlighting the synthetic utility of the reported protocol.

Supporting Information



Publication History

Received: 30 July 2023

Accepted after revision: 22 August 2023

Accepted Manuscript online:
22 August 2023

Article published online:
28 September 2023

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