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

The orchid Coelogyne uniflora afforded earlier a steroidal ester, uniflorin. Further investigation of this orchid has now resulted in the isolation of two new phenanthropyrone derivatives, unifloranthrone and uniflorinanthrone, besides flavidin (1a), flavidinin (1c), isoflvidinin (1d) and oxoflavidin (1e). The structures of unifloranthrone and uniflorinanthrone were established as 2,7-dihydroxy-5H-phenanthro[4,5-bcd]pyran-5-one (2a) and 2,7-dimethoxy-5H-phenanthro[4,5-bcd]pyran-5-one (2c), respectively, from spectral and chemical evidence. Chemical investigation of the orchid Ione paleacea yielded two flavanone derivatives, 5,7-dihydroxy-6-methoxy-2-phenyl-2,3-dihydro-4H-1-benzopyran-4-one (3a) and 5,7-dihydroxy-6-methoxy-2-(4′-hydroxyphenyl)-2, 3-dihydro-4H-1-benzopyran-4-one (3c), besides the known stilbenoids, 3-hydroxy-5-methoxybibenzyl (4a), batatasin-III (4c) and gigantol (4e). The orchid Acrochoene punctata afforded two known bibenzyl derivatives, viz. 3,4′-dihydroxy-5-methoxybibenzyl (4f) and 4,4′ -dihydroxy-3,5-dimethoxybibenzyl (4g). Additional NMR spectral evidence was provided for further confirmation of the structures of 3a, 3c, 4a and 4g.

GENERAL

Chemistry

Journal of the Indian Chemical Society

Stilbenoids and flavonoids from the orchids Coelogyne uniflora, Ione paleacea and Acrochoene punctata

Aerobic oxidative coupling of phenol, catechol, resorcinol and pyrogallol with CuCl(OH).TMEDA as catalyst affords 2',4-dihydroxybiphenyl (1a), 3,3',4,4'-tetrahydroxybiphenyl (2a), 2,2',4,4'-tetrahydroxybiphenyl (3a) and 2,2',4,6'-tetrahydroxybiphenyl (4a) and 2',3,3',4,4',5-hexahydroxybiphenyl (5a), respectively, in moderate yields. Similar catalytic aerobic oxidative coupling of the naturally occurring phenanthrols, nudol (6a) [2,7-dihydroxy-3,4-dimethoxyphenanthrene], 2,7-dihydroxy-3,4,6-trimethoxyphenanthrene (6b) and cirrhopetalin (7) [7-hydroxy-4-methoxy-2,3-methylenedioxyphenanthrene] with the same reagent gives the corresponding 1,1'-biphenanthryls 8a and 8c and the 8,8'-biphenanthryl 9a, respectively, in very good yields. All these reactions exhibit a high degree of regioselectivity.

Catalytic aerobic oxidative coupling of some simple phenols and natural phenanthrols with CuCl(OH).TMEDA

Friedel-Crafts reaction with some monoaryl and diaryl carbinols have been studied. The products suggest a rational mode of formation of trityl alcohol and anthracene derivatives modifying the earlier reported conjecture of their formation from carbon monoxide, generated from benzhydrol and solvent benzene. It now appears that during Friedel-Crafts reaction the benzyl carbocation generated from benzhydrol may be arylated to triphenylmethane derivative. The latter under the experimental condition forms trityl cation which abstracts the hydroxyl group from the benzhydrol to form benzyl carbocation and trityl alcohol. Benzyl carbocations act both as a nucleophile and an eletrophile and dimerize to form anthracene derivatives. Incidentally, a one-pot synthesis of 10-methylbenzo[a]fluoranthene (26), characterized by NOE, decoupling and mass spectral studies, has been achieved in good yield by the Friedel-Crafts reaction of 9-fluourenol, thus providing a simple method of its synthesis.

Friedel-Crafts Reaction with Arylcarbinols : One-Pot Synthesis of 10-Methylbenzo[a]fluoranthene

Thunalbene, a new stilbene derivative, was isolated from the orchid Thunia alba which also afforded six known stilbenoids: batatasin-III, lusianthridin, 3,7-dihydroxy-2,4-dimethoxyphenanthrene, 3,7-dihydroxy-2,4,8- trimethoxyphenanthrene, cirrhopetalanthrin and flavanthrin. The structure of thunalbene, the first stilbene derivative isolated so far from an Orchidaceae plant, was established as 3,3'-dihydroxy-5-methoxystilbene from spectral and chemical evidence.

Phytochemistry

Thunalbene, a stilbene derivative from the orchid Thunia alba

Two new bibenzyl derivatives were isolated from the orchid Bulbophyllum protractum and designated bulbophyllin and bulbophyllidin. In addition batatasin-III (3,3'-dihydroxy-5-methoxy bibenzyl), 3,3',5-trimethoxybibenzyl, aloifol-I (3',4-dihydroxy-3,5-dimethoxybibenzyl), 3,3'-dimethoxy-4,5- methylenedioxybibenzyl, flavidin (2,7-dihydroxy-9,10-dihydro-5H- phenanthro[4,5-bcd]pyran), dihydroconiferyl alcohol, stigmasterol and sitosterol were isolated. The structures of bulbophyllin and bulbophyllidin were established as 2,3'-dihydroxy-3 methoxy-4,5-methylenedioxybibenzyl and 2,3'-dihydroxy-3,5-dimethoxybibenzyl, respectively, from spectral and chemical evidence.