1 H - NMR ( 300 MHz , CDCl 3 ) σ 1 . 10 ( t , 3 H , J = 6 . 6 Hz ) , 1 . 39 ( t , 3 H , J = 6 . 9 Hz ) , 1 . 66 ( br , 3 H ) , 2 . 79 ( s , 3 H ) , 3 . 21 ( br , 2 H ) , 4 . 40 ( m , 2 H ) , 5 . 10 ( q , 1 H , J = 6 . 0 Hz ) , 7 . 35 - 7 . 49 ( m , 4 H ) ;