- Synthesis, antimalarial and antileishmanial activity of novel 13-benzyl-15,16-bisnorlabdane derivatives
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Twelve 13-benzyl-15,16-bisnorlabdanes in which the C-13 and C-14 substituents are varied have been prepared from the naturally occurring labdane diterpene (+)-manool. These synthesised compounds were evaluated for antimalarial activity, in vitro as hemozo
- Salazar, Franklin J.,Quintero, Alberto,De Dominguez, Neira Gamboa,Concepcion, Juan L.,Acosta, Maria E.,Tropper, Eleonora,Villamizar, Jose E.
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- The synthesis of Ambrox-like compounds starting from (+)-larixol
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The oxidation of the (3-hydroxy-3-methyl-4-pentenyl)-side chain at C(9) of some labdanic diterpenoids with potassium permanganate was investigated. Triols, ketones, or cyclic enol ethers are the main reaction products, strongly influenced by the substituent at C(8). Further degradation of the methyl ketones by the Baeyer-Villiger reaction and modification of the exocyclic 8(17) double bond lead to suitable intermediates, which have been transformed into Ambrox-like compounds. Synthetic routes using palladium catalyzed elimination or isomerization of allylic acetates, followed by ozonolysis have been developed as well for shortening of the side chain of (+)-larixol. Products from both routes have been cyclized to 6α-hydroxy Ambrox. This compound was used as the key intermediate for the synthesis of several other Ambrox-like compounds of which some showed pleasant odour properties.
- Bolster, Marjon G,Jansen, Ben J.M,De Groot, Aede
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- Facile and simple synthesis of ring C aromatic diterpenes: Synthesis of (+)-13-hydroxypodocarpa-8,11,13-triene and (+)-7-deoxynimbidiol
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A convenient synthesis of the natural (+)-13-hydroxypodocarpa-8,11,13- triene 1 and (+)-7-deoxynimbidiol 2 from (+)-manool 4 has been achieved in good overall yield.
- Villamizar, Jose E.,Gamez, Carlos,Alcala, Antonio,Salazar, Franklin,Tropper, Eleonora,Angarita, Ana,Canudas, Nieves
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experimental part
p. 1733 - 1741
(2011/06/21)
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- Process for the preparation of ketones by ozonolysis
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The invention relates to a process for the preparation of a ketone from a tertiary alcohol having a double bond in the alpha position, that includes the step of contacting tertiary alcohol having a double bond in the alpha position with ozone in the presence of an inorganic base under ketone-forming reaction conditions.
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Page/Page column 6
(2008/06/13)
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- New access to sesquiterpene hydroquinones: Synthesis of (+)-ent-chromazonarol
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A facile access to optically active (+)-ent-chromazonarol ent-1, isolated from the sponge Disidea pallescens, is reported from commercially available (+)-manool 4. Copyright Taylor & Francis LLC.
- Villamizar, Jose,Plata, Federico,Canudas, Nieves,Tropper, Eleonora,Fuentes, Juan,Orcajo, Angel
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p. 311 - 320
(2007/10/03)
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- First formal synthesis of (+)-nimbidiol. Synthesis, X-ray structure and anticancer activity of a novel ring C aromatic diterpene: Dimethyl (+)-podocarpa-8,11,13-triene-12,13-dicarboxylate
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A novel ring C aromatic diterpene (4) has been prepared in three steps from natural (+)-manool (1). The structure and anticancer activity data for 4 has been investigated. This key intermediate (4) was easily transformed into 7-deoxo nimbidiol dimethyl ether (8). The present work represents the first formal synthesis of (+)-nimbidiol (10).
- Zambrano, Jorge L.,Rosales, Viale,Nakano, Tatsuhiko
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p. 1859 - 1862
(2007/10/03)
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- Facile Access to Optically Active Labdane-Type Diterpenes from (+)-Manool. Synthesis of (+)-Coronarin E, (+)-15,16-Epoxy-8(17),13(16),14-labdatriene, and (+)-Labda-8(17),13(Z)-diene-15,16-diol
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An efficient method for the synthesis of (+)-coronarin E (1), (+)-15,16-epoxy-8(17),13(16),14-labdatriene (2), and (+)-labda-8(17),13(Z)-diene-15,16-diol (3) from (+)-manool is described.
- Villamizar, Jose,Fuentes, Juan,Salazar, Franklin,Tropper, Eleonora,Alonso, Randolph
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p. 1623 - 1627
(2007/10/03)
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- Bifunctional abietadiene synthase: Free diffusive transfer of the (+)-copalyl diphosphate intermediate between two distinct active sites
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Abietadiene synthase (AS) catalyzes two sequential, mechanistically distinct cyclizations in the conversion of geranylgeranyl diphosphate to a mixture of abietadiene double bond isomers as the initial step of resin acid biosynthesis in grand fir (Abies grandis). The first reaction converts geranylgeranyl diphosphate to the stable bicyclic intermediate (+)-copalyl diphosphate via protonation-initiated cyclization. In the second reaction, diphosphate ester ionization-initiated cyclization generates the tricyclic perhydrophenanthrene-type backbone, and is directly coupled to a 1,2-methyl migration that generates the C13 isopropyl group characteristic of the abietane family of diterpenes. Using the transition-state analogue inhibitor 14,15-dihydro-15-azageranylgeranyl diphosphate, it was demonstrated that each reaction of abietadiene synthase is carried out at a distinct active site. Mutations in two aspartate-rich motifs specifically delete one or the other activity and the location of these motifs suggests that the two active sites reside in separate domains. These mutants effectively complement each other, suggesting that the copalyl diphosphate intermediate diffuses between the two active sites in this monomeric enzyme. Free copalyl diphosphate was detected in steady-state kinetic reactions, thus conclusively demonstrating a free diffusion transfer mechanism. In addition, both mutant enzymes enhance the activity of wild-type abietadiene synthase with geranylgeranyl diphosphate as substrate. The implications of these results for the kinetic mechanism of abietadiene synthase are discussed.
- Peters,Ravn,Coates,Croteau
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p. 8974 - 8978
(2007/10/03)
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- Concomitant bromination and lactolisation of unsaturated diols with sodium bromite in aqueous acetic acid
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The attempted lactonisation of unsaturated diols 8, 13, and 15 using sodium bromite in aqueous acetic acid gave the bromo lactols 9, 16, and 18 respectively. The bromo lactols were converted to their corresponding lactones 10, 17, and 19 using Jones reagent.
- Evans, Gary B.,Grant, Peter K.
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p. 4709 - 4712
(2007/10/03)
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- Novel Diastereoselective Routes for the Synthesis of the Ambergris ketals
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New processes have been developed which allow the stereoselective syntheses of the ambergris ketals 8α,13;13,17-diepoxi-14,15-dinorlabdane 1 and 8β,13;13,17-diepoxi-14,15-dinorlabdane 2, through selection of the appropriate catalyst for the δ,ε-epoxycarbonyl rearrangement of the key intermediate 3, which is, in turn, obtained by controlled oxidation of anticopalic acid 6.
- Costa, Maria do Ceu,Tavares, Regina,Motherwell, William B.,Curto, Maria Joao Marcelo
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p. 8839 - 8842
(2007/10/02)
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- Ozonolysis of Derivatives of Labda-8(17),14-dien-13-ol (Manool) and Their Conversion into Large Ring Unsaturated Lactones
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Dehydration of the unstable hydroperoxy ethers (4) and (6) formed on ozonolysis of the manool derivatives (2) and (5) resulted in the formation of the ten-membered unsaturated lactones (11) and (12) in good yield.The results of an investigation into the nature of the hydroxyl group and its spatial relationship to the exocyclic double bond in lactone formation are reported for other manool derivatives.
- Grant, Peter K.,Lai, Chee Kong,Prasad, J. Siva,Yap, Tho Man
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p. 711 - 725
(2007/10/02)
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- Plasmid-determined Transformation of cis Abienol and Sclareol in Nocardia restricta JTS-162
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The cis-abienol-transformable bacterium JTS-162 was identified as Nocardia restricta.This bacterium has three plasmids (pCA1, pCA2 and pCA3).Two types of cured strains were obtained by mitomicin C treatment or growth at the maximum temperature; one type had two plasmids (pCA2 and pCA3) and the other type had no plasmid.These two types of cured strains lost the ability to oxidize C-18 methyl and to split the A-ring of cis-abienol.These two types of cured strains were also devoid of the ability to oxidize the C-18 methyl of sclareol.From these results, it was considered that C-18 methyl oxidation and A-ring splitting of these labdanes were determined by plasmid pCA1 in N. restricta JTS-162.
- Hieda, Tadaharu,Mikami, Yoichi,Obi, Yukiteru,Kisaki, Takuro
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p. 3055 - 3062
(2007/10/02)
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