Application of 2D NMR Spectroscopy in Structural Elucidation of some Phenanthrene Derivatives from Indian Orchidaceae Plants

Department of Chemistry, University College of Science, 92 Acharya Prafulla Chandra Road, Calcutta-700 009

Manuscript received 15 September 1997

The structures of the phenanthrene derivatives confusarin (2,7-dihydroxy-3,4,8-trimethoxyphenanthrene) and confusaridin (2,6- dihydroxy-3,4,7,8-tetramethoxyphenantbrene), bulbophyllantbrin (3,5-dihydroxy-2,4-dimetho-xyphenanthrene), gymnopusin (2,7 -dibydroxy-3,4,9-trimethoxyphenanthrene) and cirrhopetalanthrin (2,2 ',7, 7' -tetrahydroxy-4,4' -dimethoxy-1,1 '-biphenanthryl) [isolated from the Indian Orchidaceae plants Eria confusa, Bulbophyllum leopardium, Bulbophyllum gymnopus and Cirrhopetalum maculosum respectively] deduced mainly from ¹H and ¹³C nmr spectral evidence have been established unequivocally from both homonuclear (¹H-¹H) and heteronuclear (¹H-¹³C) 2D nmr correlation studies.