1 H NMR ( 300 MHz , DMSO - d 6 ) δ 1 . 44 - 1 . 61 ( 1 H , m ) , 1 . 76 - 2 . 02 ( 3 H , m ) , 3 . 41 - 3 . 55 ( 4 H , m ) , 3 . 78 - 3 . 96 ( 2 H , m ) , 5 . 13 ( 2 H , s ) , 5 . 72 ( 1 H , s ) , 6 . 91 - 7 . 01 ( 2 H , m ) , 7 . 10 - 7 . 19 ( 1 H , m ) , 7 . 24 - 7 . 34 ( 4 H , m ) , 7 . 44 ( 1 H , td , J = 8 . 0 , 5 . 8 Hz ) .