Semisynthesis and absolute configuration of a novel rearranged 19,20-δ-lactone (9βH)-pimarane diterpene

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dc.creatorBrito, Maria Vieira de
dc.creatorMarques, Ricardo de Araújo
dc.creatorMattos, Marcos Carlos de
dc.creatorAlvarenga, Meiry Edivirges
dc.creatorValdo, Ana Karoline Silva Mendanha
dc.creatorOliveira, Maria da Conceição Ferreira de
dc.creatorMartins, Felipe Terra
dc.date.accessioned2023-11-29T11:29:09Z
dc.date.available2023-11-29T11:29:09Z
dc.date.issued2018
dc.description.abstractAnnona­lide (3β,20-ep­oxy-3α,16-dihy­droxy-15-oxo-7-pimaren-19,6β-olide, C20H26O6, 1) is the major (9βH)-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 (9βH)-pimarane backbone and report here the semisynthesis and absolute configuration of a novel rearranged 19,20-δ-lactone (9βH)-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 (3β,6β,16-trihy­droxy-7-pimaren-19,20β-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.
dc.identifier.citationBRITO, M. V. et al. Semisynthesis and absolute configuration of a novel rearranged 19,20-δ-lactone (9βH)-pimarane diterpene. Acta Crystallographica. Section C: structural chemistry, Chester, v. 74, p. 870-875, 2018. DOI: 10.1107/S2053229618009452. Disponível em: https://scripts.iucr.org/cgi-bin/paper?S2053229618009452. Acesso em: 3 nov. 2023.
dc.identifier.doi10.1107/S2053229618009452
dc.identifier.issne- 2053-2296
dc.identifier.urihttps://scripts.iucr.org/cgi-bin/paper?S2053229618009452
dc.language.isoeng
dc.publisher.countryGra-bretanha
dc.publisher.departmentInstituto de Química - IQ (RMG)
dc.rightsAcesso Restrito
dc.subjectSemisynthesis
dc.subjectNatural product
dc.subjectAbsolute configuration
dc.subjectRearrangment
dc.subjectCrystal structure
dc.subject19,20-δ-lactone (9βH)-pimarane
dc.subjectAnnona­lide
dc.subjectCassimirella ampla
dc.titleSemisynthesis and absolute configuration of a novel rearranged 19,20-δ-lactone (9βH)-pimarane diterpene
dc.typeArtigo

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