1 H NMR ( 500 MHz , DMSO - d 6 ) δ 15 . 20 ( s br , 1 H ) , 8 . 21 ( s , 1 H ) , 7 . 44 ( dd , J = 8 . 5 , 7 . 5 Hz , 2 H ) , 7 . 25 ( d , J = 8 . 7 Hz , 2 H ) , 7 . 19 ( t , J = 7 . 4 Hz , 1 H ) , 7 . 16 - 7 . 10 ( m , 4 H ) , 6 . 76 ( dd , J = 16 . 7 , 10 . 5 Hz , 1 H ) , 6 . 55 ( t , J = 6 . 1 Hz , 1 H ) , 6 . 41 ( s , 2 H ) , 6 . 09 ( s , 2 H ) , 6 . 05 ( dd , J = 16 . 7 , 2 . 4 Hz , 1 H ) , 5 . 63 ( dd , J = 10 . 5 , 2 . 4 Hz , 1 H ) , 4 . 36 ( d , J = 12 . 3 Hz , 1 H ) , 4 . 00 ( d , J = 13 . 0 Hz , 1 H ) , 3 . 20 ( t , J = 6 . 6 Hz , 2 H ) , 2 . 97 ( t , J = 12 . 4 Hz , 1 H ) , 2 . 57 ( t , J = 11 . 9 Hz , 1 H ) , 1 . 87 - 1 . 77 ( m , 1 H ) , 1 . 66 - 1 . 56 ( m , 2 H ) , 1 . 03 - 0 . 89 ( m , 2 H ) .