Napredna pretraga

Pregled bibliografske jedinice broj: 787267

Reactivity of cations and zwitterions formed in photochemical and acid-catalyzed reactions from m-hydroxycycloalkyl substituted phenol derivatives


Cindro, Nikola; Antol, Ivana; Mlinarić-Majerski, Kata; Halasz, Ivan; Wan, Peter; Basarić, Nikola
Reactivity of cations and zwitterions formed in photochemical and acid-catalyzed reactions from m-hydroxycycloalkyl substituted phenol derivatives // Journal of organic chemistry, 80 (2015), 24; 12420-12430 doi:10.1021/acs.joc.5b02297 (međunarodna recenzija, članak, znanstveni)


Naslov
Reactivity of cations and zwitterions formed in photochemical and acid-catalyzed reactions from m-hydroxycycloalkyl substituted phenol derivatives

Autori
Cindro, Nikola ; Antol, Ivana ; Mlinarić-Majerski, Kata ; Halasz, Ivan ; Wan, Peter ; Basarić, Nikola

Izvornik
Journal of organic chemistry (0022-3263) 80 (2015), 24; 12420-12430

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Excited state proton transfer (ESPT) ; carbocations ; zwitterions ; DFT ; laser flash photolysis ; m-quinone methide

Sažetak
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.

Izvorni jezik
Engleski

Znanstvena područja
Kemija



POVEZANOST RADA


Projekt / tema
098-0982933-2911 - Kavezasti spojevi: ugradbene jedinice u molekularnim sustavima (Kata Majerski, )
HRZZ-02.05/25 - Fotokemija policikličkih molekula: od istraživanja mehanizma reakcije do novih lijekova i medicinskih primjena (Nikola Basarić, )
HRZZ-IP-2014-09-6312 - Supramolekulska kontrola fotokemijskih reakcija eliminacije (Nikola Basarić, )

Ustanove
Institut "Ruđer Bošković", Zagreb

Časopis indeksira:


  • Current Contents Connect (CCC)
  • Web of Science Core Collection (WoSCC)
    • Science Citation Index Expanded (SCI-EXP)
    • SCI-EXP, SSCI i/ili A&HCI
  • Scopus


Citati