1 H NMR ( DMSO - d 6 , 400 MHz ) δ 8 . 59 - 8 . 54 ( m ) , 7 . 21 - 7 . 13 ( m ) , 4 . 53 - 3 . 38 ( m ) , 4 . 09 ( s ) , 2 . 8 - 2 . 6 ( m ) , 2 . 49 - 2 . 25 ( m ) , 1 . 75 - 1 . 58 ( m ) , 1 . 61 ( d , J = 6 . 4 Hz ) , 1 . 49 ( d , J = 6 . 5 Hz ) , 1 . 40 ( d , J = 6 . 1 Hz ) , 0 . 76 ( d , J = 6 . 3 Hz ) ;