ChemInform Abstract: SYNTHESES OF PASHANONE AND ITS ISOMERS AND THEIR DERIVATIVES

Bhaskar, Anil; Seshadri, T. R.

doi:10.1002/chin.197444205

Cited by 3 publications

(4 citation statements)

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“…The properties of l a and 2a are consistent with reported data [2] for their synthetic analogues. A double bond at C-4' would indeed generate precisely 2 homoallylic methylenes at C-2' and 7'.…”

supporting

confidence: 88%

4-Hexadecenylphenol and Flavonoids from Piper hispidum

Vieira¹,

Alvarenga²,

Gottlieb³

et al. 1980

Planta Med

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Branches and leaves of Piper hispidumSw, var. obliquum TR. YUNKER (Piperaceae) from Pari State, Brasil, contain 2',3'-dihydroxy-4',6'-dimethoxyand 2'-hydroxy-3',4',6'-trimethoxy-chalcones, as well as 6-hydroxy-5,7-dimethoxy-, 8-hydroxy-5,7-dimethoxy-and 5,7,8-trimethoxy-flavanones, besides 4-(5'E-n-hexadeceny I)-phenol. Results and DiscussionPiper hispidum Sw, var obliquum Tn. YUNKER (Piperaceae) is a shrub which occurs near BelCm, Pari.Fractionation of a C6H6-extract of branches and leaves yielded 5 flavonoids, the chalcones l a , I b and the flavanones 2a, Zb, 2c, as well as the alkyl-phenol3. The formulae of the flavonoids, deduced ' Pan 111 in the series ,.The Chemistry of Brazilian Piperaceaeu. For Part I1 see ref. [I]. Based on pan of the M.S. thesis submitted bv P.C.V. to Universidade d e S i o Paulo (1978). by PMR and MS, suggested interconversion experiments. T h e results are registered in Scheme I. The additional flavanone 2c, C,,H,O(OH)(OMe), m p 147-149", is an isomer of 2a, m p 148-1 50".T h e constitutional difference between 2a and 2c cannot be assigned unambiguously by spectra. The PMR of both flavanones include the typical signals for an ABX system with the X-part at 6 5.5 (dd, J = 11, 6 Hz), for an unsubstituted B-ring with a 5 proton singlet at 6 7.5, for two methoxyls and for an unchelated hydroxyl (6 ca. 5.5). The hydroxyl can thus not be located at C-5, a fact which is confirmed by the absence of an AICI, UV shift. It can also not be located at C -7, since the signal due to the sole aromatic proton on ring A neither of 2a, nor of 2c is shifted significantly upon acetylation. The hydroxyl and this proton must thus be meta-related. This evidence is consistent with two constitutions which, at this stagf, in view of the near identity of the Ar-H singlets (2a 6 6.27, 2c 6.26) cannot be assigned t o compounds.Heruntergeladen von: University of British Columbia. Urheberrechtlich geschützt.

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supporting

confidence: 88%

4-Hexadecenylphenol and Flavonoids from Piper hispidum

Vieira¹,

Alvarenga²,

Gottlieb³

et al. 1980

Planta Med

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“…Catalytic hydrogenation of pashanone gave 2',6'-dihydroxy-4',5'-dimethoxydihydrochalcone [1], which was indistinguishable from the natural product in all respects. This compound is known as dihydropashanone (7), but this is the first time it has been reported from a natural source.…”

mentioning

confidence: 99%

Two New Dihydrochalcones from Lindera erythrocarpa

Ichino¹,

Tanaka²,

Itô³

et al. 1988

J. Nat. Prod.

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“…A number of chalcones containing hydroxyl groups at C(2 0 ), C(2 0 ,4 0 ) or C(2 0 ,4) are known as potentially therapeutic agents against infections with methicilin-resistant Staphylococcus aureus strains (Alcaraz et al, 2000). Therefore, some chalcone derivatives have been successfully synthesized, including 2 0 ,4 0dihydroxy-5 0 ,6 0 -dimethoxychalcone (I) (Bhaskar & Seshadri, 1974). However, only a few structures of naturally occurring chalcones isolated from plants have been reported.…”

Section: Commentmentioning

confidence: 99%

“…Therefore, some chalcone derivatives have been successfully synthesized including 2′,4′-dihydroxy-5′,6′-dimethoxychalcone (I) (Bhaskar & Seshadri, 1974). However, only a few structures of naturally occurring chalcones isolated from plants have been reported.…”

Section: S1 Commentmentioning

confidence: 99%