1 H NMR ( 300 MHz , CDCl 3 ) : 6 . 87 ( s , 1 H ) , 5 . 60 ( m , 1 H , ) , 5 . 43 ( s , 1 H ) , 5 . 01 ( m , 3 H ) , 3 . 31 ( q , J = 7 . 8 Hz , 1 H ) , 3 . 02 ( t , J = 8 . 4 Hz , 1 H ) , 2 . 79 ( br , 1 H ) , 2 . 64 ( m , 1 H ) , 2 . 44 ( q , J = 8 . 1 Hz , 1 H ) , 1 . 96 ( ddd , J = 6 . 6 , 13 . 5 , 19 . 8 Hz , 1 H ) , 1 . 77 ( m , 1 H ) 13 C NMR ( 75 MHz , CDCl 3 ) : δ 194 . 9 , 140 . 7 , 137 . 8 , 116 . 6 , 104 . 0 , 102 . 1 , 79 . 8 , 54 . 5 , 51 . 6 , 49 . 5 , 44 . 9 , 37 . 6 FT - IR 2359 , 1650 cm ? 1