Catalytic aerobic oxidative transformation of the phenolic 9,10-dihydrophenanthropyran derivative imbricatin with CuCI(OH). TMEDA (TMEDA = N,N-tetramethylethylenediamine)

Department of Chemistry, University College of Science, University of Calcutta,

92, Acharya Prafulla Chandra Road, Kolkata-700 009, India

E-mail: priyalalmj@hotmail.com

Manuscript received 12 July 2010, accepted 16 August 2010

Treatment of imbricatin (2,7-dihydroxy-6-methoxy-9,10-dihydro-5H-phenanthro[4,5-bcd]pyran with CuCI(OH). TMEDA (TMEDA = N,N-tetramethylethylenediamine) in CH₂CI₂ at 0-10 ºC for 20 h with stirring afforded four different compounds A, B, C and D in relatively low yields. The structures of A, B, C and D were established as 2-hydroxy-6, 7- methylenedioxy-9, 10-dihydro-5H-phenanthro[4,5-bcd]pyran (2), 2,2', 7, 7' -tetrahydroxy-6,6' -dimethoxy-9,9', 10,10' -tetrah) dro-5H,5' H-phenanthro[4,4' ,5,5' -bcd]l,l' -bipyranyl (7), 2,2', 7 ,7' -tetrahydroxy-6,6' -dimethoxy-9,9' ,10,10' -tetrahydro-5H,5' H-phenantbro[4,4' ,5,5' -bed] 1,3' -bipyranyl (8) and 2,2', 7, 7' -tetrahydro"y-6,6' -dimethoxy-9,9',10,10' -tetrahydro-5H,5' H-phenanthro[4,4',S,5'-bcd]l,8'-bipyranyl (9), respectively, by spectral and chemical evidence.