1 H - NMR ( DMSO - d 6 ) δ 8 . 46 ( s , 1 H ) , 8 . 22 ( s , 1 H ) , 7 . 53 ( s , 1 H ) , 7 . 39 - 7 . 42 ( m , 1 H ) , 7 . 34 - 7 . 35 ( m , 1 H ) , 7 . 24 - 7 . 28 ( m , 1 H ) , 5 . 90 ( d , 1 H , J = 7 . 2 Hz ) , 5 . 53 ( d , 1 H - OH , J = 6 . 4 Hz ) , 5 . 35 ( d , 1 H - OH , J = 4 . 0 Hz ) , 4 . 67 - 4 . 71 ( m , 2 H ) , 4 . 35 - 4 . 37 ( m , 1 H ) , 3 . 41 ( dd , 1 H , J = 4 . 0 , 10 . 8 Hz ) , 3 . 06 ( q , 1 H , J = 7 . 2 Hz ) , 2 . 80 ( dd , 1 H , J = 2 . 8 , 10 . 8 Hz ) ;