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Semisynthesis and absolute configuration of a novel rearranged 19,20-δ-lactone (9ßH)-pimarane diterpene.
Brito, Maria V; Marques, Ricardo A; Mattos, Marcos C; Alvarenga, Meiry E; Valdo, Ana Karoline S M; Oliveira, Maria C F; Martins, Felipe T.
Afiliação
  • Brito MV; Department of Organic and Inorganic Chemistry, Federal University of Ceará, Fortaleza, CE 60020-181, Brazil.
  • Marques RA; Department of Organic and Inorganic Chemistry, Federal University of Ceará, Fortaleza, CE 60020-181, Brazil.
  • Mattos MC; Department of Organic and Inorganic Chemistry, Federal University of Ceará, Fortaleza, CE 60020-181, Brazil.
  • Alvarenga ME; Institute of Chemistry, Federal University of Goiás, Goiânia, GO 74001-970, Brazil.
  • Valdo AKSM; Institute of Chemistry, Federal University of Goiás, Goiânia, GO 74001-970, Brazil.
  • Oliveira MCF; Department of Organic and Inorganic Chemistry, Federal University of Ceará, Fortaleza, CE 60020-181, Brazil.
  • Martins FT; Institute of Chemistry, Federal University of Goiás, Goiânia, GO 74001-970, Brazil.
Acta Crystallogr C Struct Chem ; 74(Pt 8): 870-875, 2018 08 01.
Article em En | MEDLINE | ID: mdl-30080159
Annonalide (3ß,20-epoxy-3α,16-dihydroxy-15-oxo-7-pimaren-19,6ß-olide, C20H26O6, 1) is the major (9ßH)-pimarane diterpene isolated from tubers of Cassimirella ampla, and it exhibits cytotoxic properties upon interaction with ctDNA. We have prepared new derivatives of 1 by modification of the (9ßH)-pimarane backbone and report here the semisynthesis and absolute configuration of a novel rearranged 19,20-δ-lactone (9ßH)-pimarane. Our approach was the reduction of the carbonyl groups of 1 with sodium borohydride, at positions C15 (no stereoselectivity) and C3 (stereoselective reduction), followed by rearrangement of the 6,19-γ-lactone ring into the six-membered 19,20-δ-lactone ring in 4a (3ß,6ß,16-trihydroxy-7-pimaren-19,20ß-olide monohydrate, C20H30O6·H2O). The absolute structure of the new compound, 4a, was determined unambiguously with a Flack parameter x of -0.01 (11), supporting the stereochemistry assignment of 1 redetermined here. Besides the changes in the pattern of covalent bonds caused by reduction and lactone rearrangement, the conformation of one of the three fused cyclohexane rings is profoundly different in 4a, adopting a chair conformation instead of the boat shape found in 1. Furthermore, the intramolecular hydrogen bond present in 1 is lost in new compound 4a, due to hydrogen bonding between the 3-OH group and the solvent water molecule.
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Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Idioma: En Revista: Acta Crystallogr C Struct Chem Ano de publicação: 2018 Tipo de documento: Article País de afiliação: Brasil País de publicação: Reino Unido

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Idioma: En Revista: Acta Crystallogr C Struct Chem Ano de publicação: 2018 Tipo de documento: Article País de afiliação: Brasil País de publicação: Reino Unido