Short-Lived 1,5-Biradicals Formed from Triplet 1-Alkoxy- and 1-(Benzyloxy)-9,10-anthraquinones

Autor:	Timothy J. Peelen, Ronald L. Blankespoor, Donald L. Ward, Robert P. Smart
Rok vydání:	1997
Předmět:	chemistry.chemical_classification Methyl radical General Chemistry Biochemistry Aldehyde Medicinal chemistry Catalysis Photoexcitation chemistry.chemical_compound Colloid and Surface Chemistry Reaction rate constant chemistry Alkoxy group Irradiation Methanol Triplet state
Zdroj:	Journal of the American Chemical Society. 119:461-465
ISSN:	1520-5126 0002-7863
DOI:	10.1021/ja962633c
Popis:	The cyclopropylmethyl and (trans-2-phenylcyclopropyl)methyl radical clocks were used to estimate the lifetimes of triplet state biradicals formed from substituted 1-alkoxy-9,10-anthraquinones by photoexcitation and subsequent 1,5-hydrogen atom transfer. Irradiation (350 nm) of 1-(cyclopropylmethoxy)-2-methyl-9,10-anthraquinone (1cp) in argon-purged methanol generated the primary anthrahydroquinone product (2). Upon exposure to air, 2 was rapidly converted to cyclopropanecarboxaldehyde and 1-hydroxy-2-X-9,10-anthraquinone (3). In contrast, irradiation of 1-{(trans-2-phenylcyclopropyl)methoxy}-2-benzyl-9,10-anthraquinone (1pcp) under similar conditions produced only small amounts of 3 and the corresponding aldehyde, trans-(2-phenylcyclopropyl)carboxaldehyde. In addition, products resulting from rearrangement of the 1,5-biradical to a homoallylic 1,8-biradical were also obtained. Using the known rate constant for the rearrangement of the phenylcyclopropylmethyl radical to the homoallylic radical and the obse...
Databáze:	OpenAIRE
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