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Photochemistry of polycyclic molecules: From mechanistic studies to new drugs and medicinal applications (02.05/25)
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  • Closed Access English
    Authors: 
    Nikola Cindro; Ivana Antol; Kata Mlinarić-Majerski; Ivan Halasz; Peter Wan; Nikola Basarić;
    Country: Croatia
    Project: HRZZ | Photochemistry of polycyc... (02.05/25), NSERC , HRZZ | Supramolecular control of... (IP-2014-09-6312)

    Three m-substituted phenol derivatives, each with a labile benzylic alcohol group and bearing either protoadamantyl 4, homoadamantyl 5, or a cyclohexyl group 6, were synthesized and their potential thermal acid-catalyzed and photochemical solvolytic reactivity studied, using preparative irradiations, fluorescence measurements, nanosecond laser flash photolysis, and quantum chemical calculations. The choice of m-hydroxy-substitution was driven by the potential for these phenolic systems to generate m-quinone methides on photolysis which could ultimately drive the excited state pathway, as opposed to forming simple benzylic carbocations in the corresponding thermal route. Indeed, thermal acid-catalyzed reactions gave the corresponding cations which undergo rearrangement and elimination from 4, only elimination from 5, and substitution and elimination from 6. On the other hand, photoexcitation of 4-6 to S1 in a polar protic solvent, proton dissociation from the phenol coupled by elimination of the benzylic OH (as hydroxide ion) gave zwitterions (formal m-quinone methides). The zwitterions exhibit different reactivity from the corresponding cations due to a difference in charge distribution, as shown by DFT calculations. Thus, protoadamantyl zwitterion has a less non-classical character than the corresponding cation so it does not undergo 1, 2-shift of the carbon atom, as observed in the acid-catalyzed reaction.

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Photochemistry of polycyclic molecules: From mechanistic studies to new drugs and medicinal applications (02.05/25)
Include:
The following results are related to Canada. Are you interested to view more results? Visit OpenAIRE - Explore.
1 Research products, page 1 of 1
  • Closed Access English
    Authors: 
    Nikola Cindro; Ivana Antol; Kata Mlinarić-Majerski; Ivan Halasz; Peter Wan; Nikola Basarić;
    Country: Croatia
    Project: HRZZ | Photochemistry of polycyc... (02.05/25), NSERC , HRZZ | Supramolecular control of... (IP-2014-09-6312)

    Three m-substituted phenol derivatives, each with a labile benzylic alcohol group and bearing either protoadamantyl 4, homoadamantyl 5, or a cyclohexyl group 6, were synthesized and their potential thermal acid-catalyzed and photochemical solvolytic reactivity studied, using preparative irradiations, fluorescence measurements, nanosecond laser flash photolysis, and quantum chemical calculations. The choice of m-hydroxy-substitution was driven by the potential for these phenolic systems to generate m-quinone methides on photolysis which could ultimately drive the excited state pathway, as opposed to forming simple benzylic carbocations in the corresponding thermal route. Indeed, thermal acid-catalyzed reactions gave the corresponding cations which undergo rearrangement and elimination from 4, only elimination from 5, and substitution and elimination from 6. On the other hand, photoexcitation of 4-6 to S1 in a polar protic solvent, proton dissociation from the phenol coupled by elimination of the benzylic OH (as hydroxide ion) gave zwitterions (formal m-quinone methides). The zwitterions exhibit different reactivity from the corresponding cations due to a difference in charge distribution, as shown by DFT calculations. Thus, protoadamantyl zwitterion has a less non-classical character than the corresponding cation so it does not undergo 1, 2-shift of the carbon atom, as observed in the acid-catalyzed reaction.