19-Epi-(+)-echitoveniline, a new indole alkaloid of the leaves ofAlstonia venenata R.Br., has been shown to possess the structure and absolute stereochemistry represented by 5b on the basis of spectral and chemical evidence. A mechanistic rationale for the dependence of the mode of LAH reduction of the δ-lactone 11 on its configuration at C-19 has been offered. The influence of the C-19 configuration on the chemical shift values of the C-16 carbomethoxy protons in the 19-aroyloxy-(+)-and (-)-vincadifformine alkaloids has been discussed. © 1981.

P L MAJUMDER

S JOARDAR

B N DINDA

D BANDYOPADHYAY

(NEE SAHA) S JOARDAR

A BASU

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

Structure and absolute stereochemistry of 19-epi-(+)-echitoveniline. A new indole alkaloid of the leaves of Alstonia venenata r.br.

Tetrahedron

Phytochemistry

2 STILBENOIDS FROM THE ORCHID ERIA-FLAVA

Flaccidinin, a new phenanthropyrone derivative, and oxoflaccidin, the corresponding 9,10-dihydro compound, were isolated from the orchid Coelogyne flaccida which also yielded the previously reported 9,10-dihydrophenanthropyran derivatives flaccidin and imbricatin. The structures of flaccidinin and oxoflaccidin were established from spectral evidence and by chemical correlation. © 1989.

Flaccidinin and oxoflaccidin, two phenanthrene derivatives of the orchid coelogyne flaccida

Agrostophyllin, a naturally occurring phenanthropyran derivative from Agrostophyllum khasiyanum

From the orchid Cirrhopetalum elatum was isolated a new triterpene of the cycloartane series, which was shown to be 24-methylenecycloartanyl p-hydroxycinnamate from spectral and chemical evidence. © 1985.

24-Methylene cycloartanyl p-hydroxycinnamate from the orchid Cirrhopetalum elatum

Bulbophyllanthrin, a novel phenanthrene derivative from the orchid Bulbophyllum leopardium, was shown to have the structure 1a mainly on the basis of spectral evidence including 13C and 2D NMR spectra. © 1985.

Bulbophyllanthrin, a phenanthrene of the orchid Bulbophyllum leopardium

Structures and absolute stereochemistry of (-)-echitoveniline, (-)-11-methoxyechitoveniline and (-)-11-methoxyechitovenedine, three new indole alkaloids of the vincadifformine type, isolated from the fruits and leaves of Alstonia venenata R.Br., have been established as 3b, 3c and 3d, respectively, on the basis of spectral and chemical evidence. A plausible mechanism of the LAH reduction of the δ-lactones8b and8c to the corresponding diols 9b and 9c has been discussed. © 1979.

Structures and absolute stereochemistry of (-)-echitoveniline, (-)-11-methoxyechitoveniline and (-)-11-methoxyechitovenedine-new indole alkaloids of

Echitoserpidine: A new alkaloid of the fruits of Alstonia venenata

Echitoserpine, a new 20-aroyloxy-16-methoxy vincadifformine alkaloid, has been isolated from the fruits of Alstonia venenata R.Br. and is shown to possess structure 1 on the basis of spectral and chemical evidence. © 1974.

Journal	Tetrahedron
Publisher	-
ISSN	0040-4020