1 H NMR ( 500 MHz , DMSO - d 6 ) δ 13 . 07 ( s br , 2 H ) , 8 . 01 ( s , 1 H ) , 7 . 47 - 7 . 39 ( m , 2 H ) , 7 . 24 ( d , J = 8 . 6 Hz , 2 H ) , 7 . 18 ( t , J = 7 . 4 Hz , 1 H ) , 7 . 15 - 7 . 10 ( m , 4 H ) , 6 . 77 ( dd , J = 16 . 7 , 10 . 5 Hz , 1 H ) , 6 . 06 ( dd , J = 16 . 7 , 2 . 4 Hz , 1 H ) , 5 . 69 - 5 . 58 ( m , 4 H ) , 4 . 36 ( d , J = 12 . 3 Hz , 1 H ) , 4 . 00 ( d , J = 12 . 9 Hz , 1 H ) , 3 . 19 - 3 . 14 ( m , 4 H ) , 2 . 98 ( t , J = 12 . 3 Hz , 1 H ) , 2 . 58 ( t , J = 11 . 8 Hz , 1 H ) , 1 . 89 - 1 . 78 ( m , 1 H ) , 1 . 66 - 1 . 56 ( m , 2 H ) , 1 . 03 - 0 . 88 ( m , 2 H ) .