New Phenolics from <i>Polygala fallax</i>

Ma, Wenzhe; Wei, Xiaoyi; Ling, Tie-Jun; Xie, Haihui; Zhou, Wei

doi:10.1021/np020467i

Cited by 18 publications

(10 citation statements)

References 5 publications

(7 reference statements)

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“…Finally, according to the procedure of Hashimoto and co‐workers,2 compound 3 was transformed into polygalolide A ( 1 ) through Mukaiyama‐aldol‐type condensation with dimethyl acetal 43 and then deprotection of the acetate. The spectroscopic data of the synthesized compound were identical to those of natural polygalolide A ( 1 ) with the exception of the value of optical rotation 1. The synthetic [α] D value (=−491, c =0.0226 in MeOH) was also consistent with that reported by Hashimoto and co‐workers (=−499.9, c =0.022 in MeOH) 2…”

Section: Resultssupporting

confidence: 85%

“…Polygalolides A ( 1 ) and B ( 2 ) were isolated by Wei and co‐workers in 2003 from the powdered dried roots and stems of the folk medicinal plant Polygala fallax Hemsl. (Polygalaceae) and is used as a tonic or as an antihepatitis drug (Scheme ) 1. Extensive spectroscopic analysis has revealed that these two molecules represent a new type of phenolic compound with a distinctive tetracyclic substructure that is characterized by a highly substituted oxabicyclo[3.2.1]octanone skeleton, contiguous quaternary stereogenic centers that are fused with a γ‐lactone, and a six‐membered ether.…”

Section: Introductionmentioning

confidence: 99%

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Stereocontrolled Total Synthesis of Polygalolide A

Yamada¹,

Adachi²,

Isobe³

et al. 2013

Chemistry An Asian Journal

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The total synthesis of polygalolide A, a secondary metabolite that was isolated from a Chinese medicinal plant, is reported. A key issue in this synthesis was construction of an oxabicyclo[3.2.1] skeleton, which was solved by the development of an intramolecular Ferrier-type C-glycosylation of a glucal with siloxyfuran as an internal nucleophile. The substrate was prepared from D-glucal by the introduction of trimethylsilylacetylene and siloxyfuran groups. Although C-glycosylation did not occur under the conditions found from model experiments, further examination revealed that the combination of trimethylsilyl trifluoromethanesulfonate (TMSOTf) and 2,4,6-collidine successfully afforded the desired product as a single diastereomer. The siloxy group at the C3 position played a crucial role in the stereocontrol of this reaction. The product was further transformed into a tetracyclic compound as follows: The vinyl ether and acetylenic moieties were reduced and the siloxy group was removed with a Barton-McCombie reaction. The construction of the six-membered ether and the γ-lactone provided the tetracyclic compound. Finally, a phenolic moiety was introduced by using a Mukaiyama aldol reaction to furnish polygalolide A.

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Section: Resultssupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Stereocontrolled Total Synthesis of Polygalolide A

Yamada¹,

Adachi²,

Isobe³

et al. 2013

Chemistry An Asian Journal

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“…In 2003, Wei and co‐workers reported the isolation and structural elucidation of the polygalolides A ( 1 ) and B ( 2 ) obtained from Polygala fallax Hemsl., a medicinal plant from which extracts are used as tonics and antihepatitis drugs in China 1. The structure and relative configuration of the polygalolides were determined on the basis of NMR spectroscopic data.…”

Section: Methodsmentioning

confidence: 99%

Total Synthesis and Absolute Stereochemistry of Polygalolides A and B

Nakamura¹,

Sugano²,

Kikuchi³

et al. 2006

Angew Chem Int Ed

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In 2003, Wei and co-workers reported the isolation and structural elucidation of the polygalolides A (1) and B (2) obtained from Polygala fallax Hemsl., a medicinal plant from which extracts are used as tonics and antihepatitis drugs in China.[1] The structure and relative configuration of the polygalolides were determined on the basis of NMR spectroscopic data. However, the issue of the absolute stereochemistry of the molecules has not been resolved. The structural complexity of these molecules, which include an unprecedented trioxatetracyclic ring system and contiguous quaternary stereogenic centers at C2 and C8, poses a considerable synthetic challenge. Herein, we describe the first total synthesis of (À)-polygalolides A (1) and B (2). The synthesis takes advantage of a transformation consisting of a tandem carbonyl ylide formation/1,3-dipolar cycloaddition, which has been extensively studied, especially in the research group of Padwa. [2][3][4][5] Our retrosynthetic analysis of the polygalolides is illustrated in Scheme 1. We elected to introduce the arylmethylidene moiety at a late stage in the synthesis, and the scission of the lactone ring provided 3 as a common intermediate. The tricyclic compound 3 was assumed to arise from an intramolecular 1,3-dipolar cycloaddition of carbonyl ylide 5, generated from a-diazoketone 6 in the presence of a Rh II catalyst. Compound 6 arises from homologation of the tert-butyl ester 7, which would be elaborated from the known alcohol 8, [6] which in turn can readily be obtained from d-arabinose.We initiated the synthesis by alkylating alcohol 8 with (Z)-1-bromo-4-(tert-butyldiphenylsilyl)oxy-2-butene [7] to provide the allyl ether 9 in 98 % yield (Scheme 2). The oxidative hydrolysis of the dithioacetal with iodine was followed by oxidation with NaClO 2 and esterification with (Boc) 2 O[8] to give tert-butyl ester 10 in 70 % yield over three steps. Catalytic hydrogenation of alkene 10 provided the TBDPS ether 11 in 95 % yield, and 11 was then treated with Bu 4 NF in the presence of AcOH to give alcohol 12 in 96 % yield. Installation of the C2=C3 bond was accomplished by employing a modification of the procedure reported by Ogasawara and co-workers, [9] and subsequent reduction with NaBH 4 gave alcohol 13 in 81 % yield over both steps. A two-step sequence involving mesylation and nucleophilic substitution with pmethoxyphenol was used to convert the allyl alcohol 13 into the PMP ether 14 in 78 % overall yield. The acetonide was Scheme 1. Retrosynthetic analysis of polygalolides A and B. PMP = p-methoxyphenyl, TBDPS = tert-butyldiphenylsilyl.

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“…On the other hand, anomalin A (71), a new xanthone from the marine-derived fungus Wardomyces anomalous [65], was found to be a p56 lck tyrosine kinase inhibitor. Meanwhile, 1,5-dihydroxy-3,8-dimethoxyxanthone (94) from Swertia chirata [66] and S. cuneata [67] showed significant anti-inflammatory activity in acute, sub-acute and chronic experimental models in rats [66].…”

Section: Simple Tetra-oxygenated Xanthonesmentioning

confidence: 99%

Naturally-Occurring Xanthones: Recent Developments

Vieira

Kijjoa²

2005

CMC

173

132

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A literature survey covering the report of naturally occurring xanthones from January 2000 to December 2004, with 219 references, is presented in this review. Among 515 xanthones reported in this period, 278 were new natural xanthones. These xanthones have been identified from 20 families of higher plants (122 species in 44 genera), fungi (19 species) and lichens (3 species). The structural formulas of 368 identified xanthones, their distribution and a brief mention of their biological properties are also included.

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New Phenolics from Polygala fallax

Abstract: Two new phenolic compounds, polygalolide A (1) and polygalolide B (2), together with three known xanthones were isolated from the roots and stems of Polygala fallax. The structures of 1 and 2 were elucidated on the basis of spectroscopic evidence.

Cited by 18 publications

References 5 publications

Stereocontrolled Total Synthesis of Polygalolide A

Stereocontrolled Total Synthesis of Polygalolide A

Total Synthesis and Absolute Stereochemistry of Polygalolides A and B

Naturally-Occurring Xanthones: Recent Developments

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