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SILVESTRE BUSCEMI

Photoinduced functionalization of diterpenes: photochemical behaviour of grandifloric acid in methanol and acetonitrile

  • Autori: BUSCEMI S; ROSSELLI S; BRUNO M; SCAGLIONI L; VIVONA N; PIOZZI F
  • Anno di pubblicazione: 2004
  • Tipologia: Articolo in rivista (Articolo in rivista)
  • OA Link: http://hdl.handle.net/10447/4058

Abstract

Irradiation of grandiflorolic acid (11) at λ=254 nm in acetonitrile gave the two epimers 13 and 14 through a photodecarboxylation reaction of the carboxylic group on C-4. Irradiation of compound 11 in methanol at λ=254 nm provided the transformation of the C-20 angular methyl into a carbomethoxymethyl group. In this case, unlike compounds 13 and 14, only one of the two possible isomers (15) was obtained (equatorial methyl at C-4). A mechanistic approach of this reaction in discussed, and the role of mutual stereochemistry between C-20 methyl and C-19 carboxylic group in determining the course of the reaction is pointed out.