ESIPT

The closed cycle of interconversions occurs on an ultrafast time scale. Femtosecond studies (95CPL35) of the ESIPT rearrangement of 347 (R = Me) (commercial name Tinuvin-P) carried out over a wide spectral range... 

The ESIPT mechanism of phototautomerization allows the employment of types 346 and 347 compounds and their analogs as UV stabilizers useful for synthetic polymers. Such a stabilizer -rapidly converts the energy ab-... 

QUINONE METHIDES FROM ESIPT TO UNSATURATED SYSTEMS 1.3.1 Quinone Methides from ESIPT to Carbonyls... 

QUINONE METHIDES FROM ESIPT TO UNSATURATED SYSTEMS... 

While ESIPT from a phenolic OH to a carbonyl group is a common and efficient process, the highly reversible nature of the reaction often precludes any further reactivity, except in rare cases. For this reason, this reaction is not commonly used to generate or study quinone methides. 

Quinone Methides from ESIPT to Alkenes and Alkynes... 

Uchida and Irie have reported a photochromic system based on ESIPT to an alkene carbon.82 They observed that vinylnaphthol 121 isomerizes to the ring-closed 123 when irradiated with 334 nm light ( = 0.20, Eq. 1.34). The reaction is photoreversible since irradiation of 123 (at400 nm) regenerates the starting vinylnaphthol. The authors proposed a mechanism in which ESIPT from the naphthol OH to the [3-alkenyl carbon gives intermediate o-quinone methide 122, which undergoes subsequent electrocyclic... 

The ability to photogenerate quinone methides via ESIPT from a phenol OH to an aromatic carbon atom was explored for a wider number of substrates by Wan s... 

Similar reaction pathways were recently shown to be available to the widely used chiral ligand l,l -binaphthol (BINOL) (138).87 Irradiation of BINOL in aqueous acetonitrile initiated ESIPT to the 4 -, 5 -, and 7 -ring carbons to give biaryl quinone... 

A third reaction pathway for quinone methides generated following ESIPT to aromatic carbon (in addition to H-D exchange and cyclization) was observed following the examination of the photochemistry of 9-(2 -hydroxyphenyl)anthracene... 

Lukeman, M. Veale, D. Wan, R Munasinghe, V. R. N. Corrie, J. E. T. Photogeneration of 1,5-naphthoquinone methides via excited-state (formal) intramolecular proton transfer (ESIPT) and photodehydration of 1-naphthol derivatives in aqueous solution. Can. J. Chem. 2004, 82, 240-253. 

Le Gourrierec, D. Ormson, S. M. Brown, R. G. Excited-state intramolecular proton transfer. Part 2 ESIPT to oxygen. Prog. React. Kinet. 1994, 19, 211-275. 

Brousmiche, D. W. Wan, P. Excited state (formal) intramolecular proton transfer (ESIPT) in p-hydroxyphenyl ketones mediated hy water. J. Photochem. Photobiol. A Chem. 2000, 130, 113-118. 

Lukeman, M. Wan, P. Excited state intramolecular proton transfer (ESIPT) in 2-phenylphenol an example of proton transfer to a carbon of an aromatic ring. J. Chem. Soc., Chem. Commun. 2001, 1004-1005. 

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