1 H NMR ( 300 MHz , CDCl 3 ) δ 1 . 27 ( d , 3 H ) , 1 . 29 ( d , 3 H ) , 1 . 63 ( m , 2 H ) , 1 . 74 ( m , 2 H ) , 1 . 94 ( m , 4 H ) , 2 . 14 ( s , 3 H ) , 2 . 30 ( t , 2 H ) , 2 . 54 ( m , 1 H ) , 2 . 84 ( brd , 2 H ) , 2 . 97 ( m , 1 H ) , 4 . 36 ( t , 2 H ) , 6 . 93 ( d , 1 H ) , 7 . 23 - 7 . 38 ( m , 6 H ) , 7 . 44 ( m , 1 H ) , 7 . 47 ( s , 1 H ) , 7 . 65 ( d , 2 H ) , 7 . 80 ( m , 1 H ) ; MS ( m / e , M +): 492