1 H NMR ( 399 . 9 MHz , CDCl 3 ) δ 1 . 48 ( 9 H , s ) , 1 . 72 - 1 . 76 ( 2 H , m ) , 1 . 90 - 2 . 01 ( 2 H , m ) , 3 . 16 - 3 . 27 ( 2 H , m ) , 3 . 99 - 4 . 13 ( 2 H , m ) , 7 . 31 ( 1 H , d ) , 7 . 76 ( 1 H , dd ) , 8 . 50 ( 1 H , d ) ; m / z = 313 [ M + H ] +.