The structures of isoflavidinin and iso-oxoflavidinin, two new modified 9, 10-dihydrophenanthrenes of the orchids Pholidota articulata, Otochilus porecta and O. fusca have been established. 13C NMR spectral analysis of isoflavidinin acetate was made to confirm its structure. © 1982.

P MAJUMDER

A K SARKAR

J CHAKRABORTI

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

Isoflavidinin and iso-oxoflavidinin, two 9,10-dihydrophenanthrenes from the orchids Pholidota articulata, Otochilus porecta and Otochilus fusca

Phytochemistry

Reptanthrin and isoreptanthrin, two new dimeric phenanthrenes, were isolated from the orchid Bulbophyllum reptans which also afforded nine known stilbenoids, viz. gymnopusin (1a) [2,7-dihydroxy-3,4,9- trimethoxyphenanthrene], confusarin (1c) [2,7-dihydroxy-3,4,8- trimethoxyphenanthrene], 2,7-dihydroxy-3,4,6-trimethoxyphenanthrene (1d) and its 9,10-dihydro derivative, flavanthrinin (1e) [2,7-dihydroxy-4- methoxyphenanthrene] and its 9,10-dihydro derivative (coelonin), 3,3'- dihydroxy-5-methoxybibenzyl (batatasin-III), cirrhopetalanthrin (2a) [2,2',7,7'-tetrahydroxy-4,4'-dimethoxy-1,1'-biphenanthryl] and its 9,9',10,10'-tetrahydro derivative (flavanthrin). The structures of reptanthrin and isoreptanthrin were established as 2,2',7,7'-tetrahydroxy- 3,3',4,4',9,9'-hexamethoxy-1,1'-biphenanthryl (2c) and 2,2',7,7'- tetrahydroxy-3,3',4,4',9,9'-hexamethoxy-1,8'-biphenanthryl (3a), respectively, from spectral and chemical evidence including their biomimetic synthesis from the congener 1a with phosphomolybdic acid (PMA) on silica gel.

Dimeric phenanthrenes from the orchid Bulbophyllum reptans

The orchid Agrostophyllum khasiyanum, which earlier yielded agrostophyllin (7-hydroxy-2,6-dimethoxy-5H-phenanthro[4,5-bcd]pyran), on further chemical investigation has now yielded four more new stilbenoids, besides imbricatin (2,7-dihydroxy-6-methoxy-9,10-dihydro-5H-phenanthro[4,5- bcd]pyran), flaccidinin (2,6-dihydroxy-7-methoxy-5H-phenanthro[4,5-bcd]pyran- 5-one), isoflaccidinin (2,7-dihydroxy-6-methoxy-5H-phenanthro[4,5-bcd]pyran- 5-one) and moscatilin (4,4'-dihydroxy-3,3',5-trimethoxybibenzyl) of previously known structures. The structures of the new stilbenoids, designated agrostophyllone, agrostophylloxin, agrostophylloxidin and agrostophyllidin, were established as 7-hydroxy-2,6-dimethoxy-5H- phenanthro[4,5-bcd]pyran-5-one, 2,6,7-trimethoxy-5H-phenanthro[4,5-bcd]pyran- 5-one, 7-hydroxy-2,5,6-trimethoxy-5H-phenanthro[4,5-bcd]pyran and 7-hydroxy- 2,6-dimethoxy-9,10-dihydro-5H-phenanthro[4,5-bcd]pyran, respectively, from spectral and chemical evidence.

Four stilbenoids from the orchid Agrostophyllum khasiyanum

Callosumin, callosuminin and callosumidin, three new stilbenoids, were isolated from the orchid Agrostophyllum callosum which earlier afforded, besides 4-hydroxy-3,5-dimethoxybenzoic acid, 10 other structurally related stilbenoids, viz. orchinol, 6-methoxycoelonin, imbricatin, flaccidin, oxoflaccidin, isooxoflaccidin, flaccidinin, agrostophyllin, callosin and callosinin. The structures of callosumin, callosuminin and callosumidin were established as 2,4,6,7-tetramethoxy-9,10 dihydrophenanthrene, 2,4,6,7- tetramethoxyphenanthrene and 2,7-dihydroxy-5-ethoxy(ax)-6-methoxy-9,10- dihydro-5H-phenanthro[4,5-bcd]pyran, respectively, from spectral and chemical evidence. Although in naming callosumidin the systematic numbering system has been adopted, for ease of comparison of the spectral results the phenanthrene numbering system for the compound and its structural analogues is used.

Three stilbenoids from the orchid Agrostophyllum callosum

Isoflaccidinin and isooxoflaccidin, new phenanthropyrone derivatives, isolated from the orchid Coelogyne flaccida were shown to be 2,7-dihydroxy-6-methoxy-5H-phenanthro [4,5-bcd] pyran-5-one and 2,7-dihydroxy-6-methoxy-9,10-dihydro-5H-phenanthro [4,5-bcd] pyron-5-one, respectively, from spectral and chemical evidence. © 1992.

Isoflaccidinin and isooxoflaccidin, stilbenoids from Coelogyne flaccida

Volucrin, a new dimeric phenanthrene derivative, was isolated from the orchid Lusia Volucris which also afforded 3',4-dihydroxy-3, 5'-dimethoxy-bibenzyl (2) and the perfumery constituents methyl 2,4-dihydroxy-6-methyl benzoate (3a) and methyl 2,4-dihydroxy-3,-6-dimethyl benzoate (3b). Volucrin was shown to have the structure 1a mainly from spectral evidence. © 1990.

Tetrahedron

Volucrin, a new dimeric phenanthrene derivative from the orchid lusia volucris

Coelonin, A 9,10-dihydrophenanthrene from the orchids Coelogyne ochracea and Coelogyne elata

Coelogin and coeloginin, two novel 9,10-dihydrophenanthrene derivatives of the high altitude Himalayan orchid Coelogyne cristata, have been shown to have the phenanthro[4,5-bcd]pyran structures (1a) and (1b), respectively, from spectral and chemical evidence.

Journal of the Chemical Society, Perkin Transactions 1

Coelogin and coeloginin: Two novel 9,10-dihydrophenanthrene derivatives from the orchid coelogyne cristata

Journal of the American Chemical Society

Carbon-13 magnetic resonance. Upfield shifts caused by nitrogen, oxygen, and fluorine atoms located at the .gamma. position and antiperiplanar to the nucleus observed

Journal	Phytochemistry
Publisher	-
ISSN	0031-9422