1 H NMR δ 0 . 9 ( d , 3 H ) , 2 . 3 - 2 . 4 ( m , 2 H ) , 2 . 5 ( s , 1 H ) , 3 . 7 ( d , 6 H ) , 4 . 0 - 4 . 1 ( br m , 1 H ) , 4 . 15 - 4 . 25 ( br m , 1 H ) , 6 . 75 - 6 . 8 ( m , 1 H ) , 6 . 85 ( m , 1 H ) , 6 . 9 - 7 . 0 ( m , 1 H ) , 7 . 65 ( s , 1 H ) , 7 . 75 ( s , 2 H ) , 9 . 1 ( s , 1 H ) , 9 . 5 ( s , 1 H ) ; MS m / z 335 . 6 ( M + H ) , 267 . 1 ( M - C 3 H 3 N 2 · )