- 2-Hydroxy-1,2,2-triphenylethanone as an efficient photolabile protecting group for carboxylic acids
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The synthesis is reported of 2-hydroxy-1,2,2-triphenylethanone esters of carboxylic acids by the reaction between 2-chloro-1,2,2-triphenylethanone and a carboxylic acid in the presence of silver carbonate and silver tetrafluoroborate. Photolysis of the esters occurs rapidly on irradiation with a medium-pressure mercury lamp through quartz or Pyrex to return the carboxylic acid. The side product of the photolysis is benzo[b]phenanthro[9,10-d]furan, formed through a tandem process involving initial generation of 2,3-diphenylbenzofuran, photochemical cyclisation and re-aromatisation by aerial oxidation.
- Ashraf, M. Arfan,Russell, Alexander G.,Wharton, Christopher W.,Snaith, John S.
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p. 586 - 593
(2007/10/03)
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- A different route to the synthesis of 9,10-disubstituted phenanthrenes
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We here report the synthesis of 10-aryl-9-hydroxy- and 10-aryl-9- aminophenanthrenes by reaction of the anions of 9-phenanthrol and 9-aminophenanthrene, respectively, with aryl halides (iodobenzene, 4-iodoanisole, 9-bromophenantrene). Good yields of 9,10-disubstituted phenanthrenes were obtained in these reactions (>75% and ～50% for the 9-amino and 9-hydroxyphenanthrene rings, respectively). Extension of the procedure to the reaction of both anions with o-dihalobenzenes leads to the synthesis of the ring closure products (aza- or oxa-indeno[1,2-l]phenanthrene), which bear a pentacyclic aromatic condensed ring system, although in lower overall yields (～35%).
- Tempesti, Tomas C.,Pierini, Adriana B.,Baumgartner, Maria T.
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p. 6508 - 6511
(2007/10/03)
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