1 H - NMR ( 300 MHz , CDCl 3 ) σ 1 . 06 ( t , 3 H , J = 6 . 9 Hz ) , 1 . 39 ( t , 3 H , J = 7 . 2 Hz ) , 1 . 68 ( br , 3 H ) , 2 . 78 ( s , 3 H ) , 3 . 15 ( br , 2 H ) , 3 . 70 ( s , 3 H ) , 3 . 77 ( s , 3 H ) , 4 . 38 ( m , 2 H ) , 5 . 16 ( q , 1 H ) , 6 . 86 ( d , 1 H , J = 9 . 3 Hz ) , 6 . 95 ( dd , 1 H , J = 3 . 0 , 9 . 3 Hz ) , 6 . 98 ( d , 1 H , J = 3 . 0 Hz ) ;