1 H NMR ( 300 MHz , DMSO - d 6 ) δ 1 . 14 ( 6 H , s ) , 1 . 65 - 1 . 86 ( 3 H , m ) , 1 . 93 - 2 . 13 ( 1 H , m ) , 2 . 99 ( 2 H , s ) , 3 . 26 - 3 . 30 ( 2 H , m ) , 3 . 41 - 3 . 61 ( 2 H , m ) , 3 . 68 - 4 . 00 ( 3 H , m ) , 7 . 29 ( 1 H , d , J = 7 . 9 Hz ) , 7 . 40 ( 1 H , s ) , 7 . 60 ( 1 H , d , J = 7 . 9 Hz ) .