Molecular Diversity

, Volume 7, Issue 2–4, pp 265–271 | Cite as

Temperature dependent photochemical cleavage of 2,5-dimethylphenacyl esters

  • Jaromír Literík
  • Stanislav Relich
  • Petr Kulhánek
  • Petr Klán

Abstract

The study of the temperature-sensitive photochemical release of a carboxylic acid from 2,5-dimethylphenacyl ester is reported. Quantum yields of the benzoate ester degradation in benzene increased from 0.22 at room temperature to 0.28 at 50 °C whereas a more significant increase (nearly by a factor of 3) was observed in methanol and ethanol, reaching a high reaction efficiency (0.25) typically found in non-polar solvents. The reaction proceeds predominantly via the triplet pathway and the E-photoenol in the whole temperature range in methanol solution. A higher quantum efficiency in heated methanol is explained by enhancing the E-photoenol population. This picture was partially confirmed by the quantum chemical calculations. The 2,5-dimethylphenacyl chromophore is proposed as an efficient photoremovable protecting group for carboxylic acids in solutions under conventional or microwave-assisted heating for applications in organic synthesis, such as the solid-phase synthesis.

microwave phenacyl esters photochemistry protecting group synthesis 

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Copyright information

© Kluwer Academic Publishers 2003

Authors and Affiliations

  • Jaromír Literík
    • 1
  • Stanislav Relich
    • 1
  • Petr Kulhánek
    • 2
  • Petr Klán
    • 1
  1. 1.Department of Organic ChemistryFaculty of Science, Masaryk UniversityBrnoCzech Republic
  2. 2.National Centre for Biomolecular Research, Faculty of ScienceMasaryk UniversityBrnoCzech Republic

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