1 H NMR ( DMSO d 6 ) δ 9 . 22 ( 1 H , br s ) , 8 . 65 ( 1 H , dt , J = 4 . 6 , 1 . 6 Hz ) , 7 . 60 - 7 . 70 ( 2 H , m ) , 7 . 36 - 7 . 49 ( 3 H , m ) , 4 . 35 - 4 . 53 ( 2 H , m ) , 3 . 79 ( 1 H , td , J = 11 . 7 , 2 . 5 Hz ) , 3 . 61 ( 1 H , dd , J = 11 . 6 , 3 . 1 Hz ) , 3 . 08 ( 1 H , d , J = 11 . 3 Hz ) , 2 . 84 ( 1 H , dt , J = 11 . 8 , 2 . 5 Hz ) , 2 . 66 ( 1 H , br d , J = 11 . 1 Hz ) , 2 . 52 - 2 . 58 ( 1 H , m ) , 2 . 32 - 2 . 47 ( 1 H , m ) , 2 . 21 ( 3 H , s ) , 1 . 90 - 2 . 16 ( 3 H , m ) .