Dendrobium gibsonii, an Orchidaceae plant yielded the first natural fluorenone derivatives designated dengibsin and dengibsinin to which 1,5-dihydroxy-7-methoxy-9-fluorenone (1) and 1,6-dihydroxy-5, 7-dimethoxy-9-fluorenonc (2) structures have been assigned respectively. The structures are fully supported by the 1 H-NMR, IR, UV and MS spectral data of dengibsin and dengibsnin and a number of their pertinent derivatives. Aurantiamide acetate, dimethyl terephthalate and β-sitosterol have been isolated as the other constituents. © 1985.

S K TALAPATRA

S BOSE

A K MALLIK

B TALAPATRA

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

On the chemistry of indian orchidaceae plants—II

Tetrahedron

A new diosgenin derivative designated denfigenin has been isolated from the petrol extract of the whole plant Dendrobium fimbriatum, along with diosgenin and defuscin (n-triacontyl p-coumarate). Denfigenin was shown to be (25R)-22α-O-spirost-5-ene-3β,16α,17α-triol mainly based on 1H and 13C NMR spectral studies. Its molecular conformation has also been discussed. © 1992.

Phytochemistry

Denfigenin, a diosgenin derivative from Dendrobium fimbriatum

9,9'-Bifluorenyl (6), 1,1,2,2-tetraphenylethane (10) and 10,10'-bianthrone (18) have been obtained as a new type of products in Clemmensen reduction of 9H-fluoren-9-one (3), benzophenone (7) and 9,10-anthraquinone (13) respectively. Dibenzo(g,p)chrysene (5) is formed as the major product in the reduction of 3. Plausible mechanistic pathways for the formation of the unconventional products have been delineated. © 1990.

Some newer aspects of Clemmensen reduction of aromatic ketones

Defuscin, a new phenolic ester shown to be n-triacontyl p-coumarate, and (-)-shikimic acid have been isolated from the whole plant of Dendrobium fuscescens Griff. The 1H NMR spectrum of shikimic acid is indicative of the weighted average of its two half-chair conformers, the one with 4-OH and 5-OH in equatorial orientations being the major contributor. © 1989.

Defuscin, a new phenolic ester from Dendrobium fuscescens: Conformation of shikimic acid

A new ester amide designated (-)-anabellamide was isolated along with 4′-hydroxydehydrokawain (2) and /3-sitosterol-/S-D-glucoside from the whole plant of Anaphalis subumbellata. (-)-AnabelIamide has been shown to be 1, the (5)-N-benzoylphenylalaninyl ester of (5)-N-benzoylphenylalanine on the basis of its spectrometric studies and its synthesis from (5)-(-)-phenylalanine. © 1983, American Chemical Society. All rights reserved.

Journal of Natural Products

Structure and synthesis of (-)-anabellamide. A new phenylalanine derived ester amide from anaphalis subumbellata: Occurrence of 4â€²-hydroxydehydrokawain

A novel methodology leading to the synthesis of (+)-triacetoxygoniotriol 2 from d-glucose is described. Construction of the core six-membered α,β-unsaturated lactone moiety involved ring closing metathesis (RCM) followed by a PCC oxidation. Later exploiting the pseudo-symmetry of d-glucose three other diastereomers of triacetoxygoniotriol were synthesized using the developed methodology. © 2006 Elsevier Ltd. All rights reserved.

RCM/PCC oxidation strategy for synthesis of functionalized cyclic α,β-unsaturated lactones: synthesis of (+)-triacetoxygoniotriol and its diastereomers

On the chemistry of indian orchidaceae plants-II 1 1 For Part I see Ref. 1. Dengibsin and dengibsinin, the first natural fluorenone derivatives from dendrobium gibsonii lindl

Journal	Tetrahedron
Publisher	-
ISSN	0040-4020