Synthesis of 6α,7β-Di-Hydroxyvouacapan-17β-Oic acid derivatives part III: synthesis, 1H- and 13C-NMR of amide derivatives1

Maltha, Célia R. A.; Stefani, G.; Piló‐Veloso, Dorila; Ferreira-Alves, Dalton L.

doi:10.1590/s0103-50531997000300003

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“…3,4 Some derivatives of 1 have been prepared for biological evaluation. 2,5,6 Here we report the preparation of the esters 4-9 (Scheme 1), and an evaluation of their phytotoxic properties.…”

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confidence: 99%

Synthesis and phytotoxicity evaluation of novel 6α,7β-dihydroxyvouacapan-17β-oic acid derivatives

Castelo-Branco

Rubinger

Resende

et al. 2006

Journal of Chemical Research

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The 6a,7b-dihydroxyvouacapan-17b-oic acid (1) isolated from Pterodon polygalaeflorus Benth has shown allelopathic and plant growth regulatory properties. Six novel esters of (1) were prepared and their effects on the radical growth of Sorghum bicolor L. and Cucumis sativus L. were evaluated.The natural product 6a,7b-dihydroxyvouacapan-17b-oic acid (1) and the lactone 2 (Scheme 1), exhibit anti-inflammatory, analgesic activities, 1 and allelopathic activity. 2 Several terpenoids are involved in plant allelopathic interactions but little is known about the effects of diterpenes on plant growth regulation. 3,4 Some derivatives of 1 have been prepared for biological evaluation. 2,5,6 Here we report the preparation of the esters 4-9 (Scheme 1), and an evaluation of their phytotoxic properties.The acid (1) was isolated from the P. polygalaeflorus Benth fruits. 7 The d-hydroxy-lactone 2 5 and d-keto-lactone 3 8 were prepared as shown in Scheme 1. The novel compounds 4-9 were prepared in good yields (77-89 %) using catalytic amounts of NaOH. The lactone 3 is not very soluble in the alcohols. Thence the end of the reaction could be observed by TLC and by the total disappearance of the solid phase.The esters 4-9 were characterised by elemental analysis, IR and NMR spectroscopy. The IR spectra of all the esters 4-9 showed a hydroxyl absorption between 3495 and 3465 cm -1 and strong C=O stretching bands in the 1735-1709 cm -1 range due to the ester and ketone groups. In the 13 C NMR spectra, the carbonyl signals were observed around d C 174 (ester) and d C 209 (ketone). The 1 H NMR signals due to the furanditerpene backbone hydrogens of the esters 4-9 are very similar to those observed in the spectrum of the parent lactone 3. 8 It is interesting to note the multiplicity of the signal at d H 1.70 in the 1 H NMR spectrum of 6 which is a sextet assigned to H-2', indicating non-resolvable coupling constants (J 7.3 Hz)with the theoretically non-equivalent hydrogens H-1' and H-3'. Other features worth mentioning are the nonequivalence of the H-1' methylenic hydrogens revealed by the double doublets observed in the 1 H NMR spectrum of compound 9 at d H 4.61 and 4.71 with Jgem 12.2 Hz and Jvic 7.2 Hz with H-2'. The remaining signals were in accordance with the proposed structures.It was previously reported that 1 at 100 ppm inhibited the root growth of Sorghum bicolor L. (30-40 %) and stimulated Cucumis sativus L. (5-10 %). 2 Recently it was shown that lactones 2 and 3 inhibited the uncoupled noncyclic electron transport and ATP synthesis, behaving as Hill reaction inhibitors, and the carbonyl at C-6 of 3 affected the photophosphorylation. 2,8 Compounds 1-9 were evaluated in vitro against S. bicolor and C. sativus using a different methodology. 9 As the compounds were not soluble in the usual formulations, 9 an aqueous solution of a triblock copolymer and DMSO was used instead. Table 1 shows the radical lengths. Under these conditions, the novel compounds and the parent lactones did not significantly affect the growth of S. bicolor.

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confidence: 99%

Synthesis and phytotoxicity evaluation of novel 6α,7β-dihydroxyvouacapan-17β-oic acid derivatives

Castelo-Branco

Rubinger

Resende

et al. 2006

Journal of Chemical Research

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“…With the aim to producing ADV derivatives without hydrogen bond donors, the amide 2 was obtained as previously reported 12 and then reacted with excess of sodium hydride to produce N-ethyl-N-methyl-6α,7β-dimethoxyvouacapan-17β-amide (amide 3, Scheme 1). This is a new compound whose structure was determined by comparison with compound 2, by means of both IR and NMR spectra analysis.…”

Section: Resultsmentioning

confidence: 99%

“…[9][10][11] Therefore, aiming to obtain information on chemical structure and biological activity relationships and to search for more potent compounds, several derivatives of ADV have been synthesized. 6,7,[12][13][14][15][16][17] The ADV presents groups that may be both donor and acceptor of hydrogen bonds. For comparison studies here we report both the synthesis and identification of six new amide derivatives (4-9) presenting only acceptor of hydrogen bonds and the results of in vitro biological screening test.…”

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confidence: 99%

Synthesis of 6alpha,7beta-dihydroxyvouacapan-17beta-oic acid derivatives. Part IV: mannich base derivatives and its activities on the electrically stimulated Guinea-pig ileum preparation

Belinelo

Reis

Stefani

et al. 2002

J. Braz. Chem. Soc.

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O ácido 6α,7β-di-hidroxivouacapan-17β-óico (ADV, 1), furanoditerpeno isolado dos frutos de Pterodon polygalaeflorus Benth, apresenta atividade analgésica em modelos laboratoriais utilizando roedores. Visando reunir dados para estudar a ação biológica de vouacapanóides, foram obtidas seis novas amidas derivadas (4-9), contendo grupos alquilaminas no anel furânico, preparadas pela reação de Mannich com sais de imínios pré-formados. Esses derivados tiveram suas estruturas determinadas pela análise de dados espectroscópicos no IV, RMN de 1 H e de 13 C e foram submetidos a triagem farmacológica in vitro, destinada a detectar substâncias com ação depressora sobre células neuronais.The furanditerpene 6α,7β-dihydroxyvouacapan-17β-oic acid (ADV, 1), isolated from Pterodon polygalaeflorus Benth fruits, presents analgesic activity in current rodent experimental models. With the aim to gather data for biological studies it were obtained six new amide derivatives substituted in the furan ring with alkylamine groups, prepared by the Mannich reaction with preformed iminium salts. These derivatives were evaluated in a preliminary in vitro pharmacological test. Structures were determined by spectroscopic data of IR, 1 H and 13 C NMR.

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“…Analgesic and anti-inflammatory activities have been observed for compound 1 [9][10][11]. The relationships between the chemical structure and the biologic activities of 1 and its derivative lactones [12][13][14][15], Mannich bases [15,16], amides [17][18][19], carbamates [20], and other compounds [21][22][23][24][25][26][27] have been investigated. These derivatives show anti-inflammatory, analgesic, sedative, anticonvulsant, and plant growth regulatory activities.…”

Section: Introductionmentioning

confidence: 99%

Theoretical and experimental NMR studies of the Swern oxidation of methyl 6α,7β-dihydroxyvouacapan-17β-oate

et al. 2008

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This work describes the synthesis of new derivatives of 6a,7b-dihydroxyvouacapan-17b-oic acid (1) employing the Swern method for the oxidation of C-6 and C-7 of methyl 6a,7b-di-hydroxyvouacapan-17b-oate (2) and the formation of methyl 6,7-dioxovouacapan-17b-oate (3). NMR structural studies associated with theoretical calculations of reaction intermediates and products are also reported. The mixture of methyl 7b-hydroxy-6-oxovouacapan-17b-oate (4; 21%) and methyl 6a-hydroxy-7-oxovouacapan-17b-oate (5; 79%) was the product from the first step of the oxidation of 2. The lower energy of 5, calculated by HF/6-31G* and DFT/BLYP/6-31G* methods, reinforces the thermodynamic control proposed for the reaction. After further Swern oxidation of the mixture of 4 and 5, the isomeric form methyl 6-hydroxy-7-oxovouacap-5-en-17b-oate (6) was obtained. Theoretical calculations indicate a lower energy for the mono-enol 6 than the 1,2-diketo 3 and the other mono-enol methyl 7-hydroxy-6-oxovouacap-7-en-17b-oate (7).

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Synthesis of 6α,7β-Di-Hydroxyvouacapan-17β-Oic acid derivatives part III: synthesis, 1H- and 13C-NMR of amide derivatives1

Cited by 4 publications

References 0 publications

Synthesis and phytotoxicity evaluation of novel 6α,7β-dihydroxyvouacapan-17β-oic acid derivatives

Synthesis and phytotoxicity evaluation of novel 6α,7β-dihydroxyvouacapan-17β-oic acid derivatives

Synthesis of 6alpha,7beta-dihydroxyvouacapan-17beta-oic acid derivatives. Part IV: mannich base derivatives and its activities on the electrically stimulated Guinea-pig ileum preparation

Theoretical and experimental NMR studies of the Swern oxidation of methyl 6α,7β-dihydroxyvouacapan-17β-oate

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