Synthetic approach to pentacyclic quassinoids from communic acids, via ambracetal derivatives

Álvarez-Manzaneda, Enrique; Romera, Juan L.; Barrero, Alejandro F.; Álvarez-Manzaneda, Ramón; Chahboun, Rachid; Meneses, R.; Aparicio, Mònica Colominas

doi:10.1016/j.tet.2004.11.034

Cited by 6 publications

(2 citation statements)

References 15 publications

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“…Total syntheses of these compounds are usually rather inefficient in view of tedious synthetic routes, expensive chiral reagents, low yields, vigorous reaction conditions, and the low optical purities obtained [8]. To date, most of these syntheses are based on transformation of terpenes such as sclareolide [9], abietic acid [10], labdanolic acid [11], sclareol [12], manool [13], larixol [14], and communic acid [15] or well-established synthetic chiral materials such as the WielandÀMiescher ketone [6a] [16]. Nevertheless, almost all these semisynthetic materials are comparatively rare and expensive, bearing no functional groups at ring A (C(1) to C(4)) and, therefore, may not be employed to synthesize compounds with functional groups at ring A. Interestingly, ursolic acid is characterized by a chiral trans-decalin framework of the rings AB and a chiral cis-decalin framework of the rings DE, which could be used as versatile precursors for a large number of natural products with similar chiral decalin units [17].…”

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confidence: 99%

Synthesis of Novel 8,14‐Secoursane Derivatives: Key Intermediates for the Preparation of Chiral Decalin Synthons from Ursolic Acid

Zhang

Yang

et al. 2012

Helvetica Chimica Acta

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The novel 8,14-secoursatriene derivative 6 was synthesized starting from ursolic acid (1) via methyl esterification of the 17-carboxylic acid group and benzoylation of the 3-hydroxy group (! 2; Scheme 1), ozone oxidation of the C(12)¼C(13) bond (! 3), dehydrogenation with Br 2 /HBr (! 4), enol acetylation of the resulting carbonyl group (! 5; Scheme 2), and ring-C opening with the aid of UV light (! 6). Ring-C-opened dienone derivative 7 of ursolic acid was also obtained via selective hydrolysis of 6 (Scheme 2). Both compounds 6 and 7 are key intermediates for the preparation of chiral decalin synthons from ursolic acid.

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confidence: 99%

Synthesis of Novel 8,14‐Secoursane Derivatives: Key Intermediates for the Preparation of Chiral Decalin Synthons from Ursolic Acid

Zhang

Yang

et al. 2012

Helvetica Chimica Acta

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“…Decalin is one of the most prevalent structural units present in natural products possessing diverse and significant biological activities and olfactory and fixative properties . To date, numerous syntheses of these kinds of compounds have been accomplished. , Most of the syntheses are based on transformation of terpenes such as sclareolide, abietic acid, labdanolic acid, sclareol, manool, larixol, and communic acid or well-established synthetic chiral materials such as Wieland−Miescher ketone . Nevertheless, almost all these semisynthetic materials are comparatively rare and expensive, bear no functional groups on ring A (C-1 to C-4), possess a Me-8β functionality, and may not be employed to synthesize compounds with functional groups on ring A or those with a Me-8α group.…”

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Chiral Decalins: Preparation from Oleanolic Acid and Application in the Synthesis of (−)-9-epi-Ambrox

Yang

Cai

et al. 2006

J. Nat. Prod.

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A novel and versatile process was developed to prepare the trans-decalins ∆ 9(11) -3 -acetoxysclareolide (2) and ∆ 9(11) -3 -acetoxy-8-epi-sclareolide (3), respectively, with 4a-methoxycarbonyl-2,7,7-trimethyl-1-oxo-cis-decalin-2-ene (4) and its C-3 hydroxyl derivative 5 from oleanolic acid (3 -hydroxyolean-12-en-28-oic acid, 1). Three key steps were (a) introduction of the AcO-12 group and the C-9,C-11 double bond at ring C of methyl 3 -acetoxyolean-12-en-28-oate (8) to afford the diene, methyl 3,12-diacetoxyolean-9(11),12-dien-28-oate (11); (b) photolytic cleavage of the C-8,C-14 bond in the diene to give an acetoxy-substituted triene 14; and (c) oxidative cleavage of the triene or its hydrolyzed R, -unsaturated ketone product with m-CPBA/TsOH to give the cis-and trans-decalins 2-5. ∆ 9(11) -3 -Acetoxysclareolide (2) was stereospecifically reduced to give 3 -acetoxy-9-epi-sclareolide (23), from which (-)-9-epi-ambrox (7) was synthesized.Decalin is one of the most prevalent structural units present in natural products possessing diverse and significant biological activities 1 and olfactory and fixative properties. 2 To date, numerous syntheses of these kinds of compounds have been accomplished.

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Ilicic Acid as a Natural Quiron for the Efficient Preparation of Bioactive α‐ and β‐Eudesmol

et al. 2009

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An efficient procedure for the isolation of the sesquiterpene ilicic acid (3) on a multigram scale of extracts obtained from aerial parts of Inula viscosa (Asteraceae) was developed. Acid 3 is an appropriate starting material for short, enantiospecific syntheses of β‐eudesmol (1) and α‐eudesmol (2), natural products featuring significant antiangiogenic and anti‐Alzheimer properties. Synthesis of 1 was achieved in six steps and the synthesis of 2 in seven, producing overall yields of 52 and 41 %, respectively.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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Synthetic approach to pentacyclic quassinoids from communic acids, via ambracetal derivatives

Cited by 6 publications

References 15 publications

Synthesis of Novel 8,14‐Secoursane Derivatives: Key Intermediates for the Preparation of Chiral Decalin Synthons from Ursolic Acid

Synthesis of Novel 8,14‐Secoursane Derivatives: Key Intermediates for the Preparation of Chiral Decalin Synthons from Ursolic Acid

Chiral Decalins: Preparation from Oleanolic Acid and Application in the Synthesis of (−)-9-epi-Ambrox

Ilicic Acid as a Natural Quiron for the Efficient Preparation of Bioactive α‐ and β‐Eudesmol

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