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    • Synthetic studies in aromatic hemiterpenes of natural origin, Part 5: Synthesis of 6-acetyl-2,2-dimethyl-8-methoxychromene via benzylic oxidation route

      M Venkama Naidu G S Krishna Rao

      Organic Volume 88 Issue 3 June 1979 pp 197-201

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      Permanent link:
      https://www.ias.ac.in/article/fulltext/jcsc/088/03/0197-0201

    • Keywords

       

      Aromatic hemiterpenes; coumarins; chromenes; benzylic oxidative dehydrogenation by DDQ

    • Abstract

       

      The synthesis of 6-acetyl-2,2-dimethyl-8-methoxychromene (1c), a naturally occurring isomer of encecalin (1a) has been described starting from 2,2,6-trimethyl-8-methoxychromene (2e) which was obtained from creosol (4) in two steps involving condensation of the phenol with malic acid to the coumarin (3), followed by Grignard reaction with CH2MgI. The transformation of (2e) to the natural product (1c) was effected by oxidative dehydrogenation by DDQ of the 6-methyl function to the formyl group (2f), Grignard reaction to the carbinol (2g) and finally its oxidation to the acetyl moiety (1c), the sequence of the essential steps schematically summarised as: Ar-CH3 → Ar-CHO → Ar-CH (OH) CH3 → Ar-COCH3.

    • Author Affiliations

       

      M Venkama Naidu1 G S Krishna Rao1

      1. Department of Organic Chemistry, Indian Institute of Science, Bangalore - 560 012

    • Dates

       
      Published
      June 1979
      Manuscript received
      19 March 1979

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