1 H - NMR ( 300 MHz , CDCl 3 ) σ 1 . 10 ( br , 3 H ) , 1 . 39 ( t , 3 H , J = 7 . 2 Hz ) , 1 . 64 ( br , 3 H ) , 2 . 78 ( s , 3 H ) , 3 . 21 ( br , 2 H ) , 4 . 40 ( q , 2 H , J = 7 . 2 Hz ) , 5 . 09 ( q , 1 H , J = 6 . 3 Hz ) , 7 . 29 ( m , 2 H ) , 7 . 58 ( d , 1 H , J = 6 . 9 Hz ) ;