1 H NMR ( 300 MHz , CDCl 3 ) δ 1 . 78 - 2 . 02 ( 3 H , m ) , 2 . 08 - 2 . 23 ( 1 H , m ) , 3 . 25 - 3 . 35 ( 2 H , m ) , 3 . 40 - 3 . 56 ( 2 H , m ) , 3 . 86 ( 3 H , s ) , 3 . 89 - 4 . 01 ( 3 H , m ) , 6 . 89 ( 1 H , dd , J = 8 . 1 , 2 . 5 Hz ) , 7 . 08 - 7 . 11 ( 1 H , m ) , 7 . 12 - 7 . 17 ( 1 H , m ) , 7 . 22 ( 2 H , d , J = 8 . 3 Hz ) , 7 . 32 - 7 . 38 ( 1 H , m ) , 7 . 53 ( 2 H , d , J = 8 . 3 Hz ) .