1 H NMR ( 300 MHz , DMSO - d 6 ) δ 0 . 81 ( 3 H , t , J = 7 . 3 Hz ) , 1 . 21 ( 3 H , d , J = 7 . 2 Hz ) , 1 . 59 ( 2 H , quin , J = 7 . 3 Hz ) , 2 . 62 ( 1 H , sxt , J = 7 . 1 Hz ) , 3 . 39 - 3 . 50 ( 2 H , m ) , 4 . 57 - 4 . 72 ( 2 H , m ) , 6 . 70 ( 1 H , t , J = 7 . 0 Hz ) , 7 . 19 - 7 . 29 ( 2 H , m ) , 7 . 40 - 7 . 49 ( 2 H , m ) , 7 . 61 ( 1 H , dd , J = 7 . 3 , 1 . 7 Hz ) , 7 . 76 ( 1 H , dd , J = 6 . 6 , 1 . 7 Hz ) .