1 H NMR ( 300 MHz , CDCl 3 ) δ 1 . 64 ( m , 2 H ) , 1 . 76 ( brd , 2 H ) , 1 . 84 - 1 . 90 ( m , 4 H ) , 2 . 16 ( s , 3 H ) , 2 . 21 ( t , 2 H ) , 2 . 39 ( s , 3 H ) , 2 . 41 ( s , 3 H ) , 2 . 42 ( m , 1 H ) , 2 . 80 ( brd , 2 H ) , 3 . 77 ( s , 3 H ) , 4 . 09 ( t , 2 H ) , 6 . 94 - 6 . 97 ( m , 2 H ) , 7 . 21 - 7 . 31 ( m , 2 H ) , 7 . 36 ( s , 1 H ) , 7 . 40 - 7 . 44 ( m , 2 H ) , 7 . 49 ( d , 1 H , J = 2 . 7 Hz ) , 7 . 55 ( s , 1 H ) ; MS ( m / e , M +): 545