1 H NMR δ 1 . 65 - 1 . 70 ( m , 2 H ) , 1 . 75 - 1 . 80 ( m , 2 H ) , 2 . 7 - 2 . 75 ( m , 2 H ) , 3 . 7 ( s , 3 H ) , 3 . 75 ( s , 3 H ) , 4 . 0 - 4 . 05 ( t , 2 H ) , 6 . 9 - 7 . 0 ( m , 2 H ) , 7 . 2 ( s , 1 H ) , 7 . 3 ( d , 1 H ) , 7 . 5 ( s , 1 H ) , 7 . 75 ( s , 1 H ) , 11 . 0 ( s , 1 H ) ; MS m / z 320 . 2 ( M + H ) , 252 . 2 ( M - C 3 H 3 N 2 · )