Treatment of 4-formylmorpholine with sulphur tetrafluoride in the presence of potassium fluoride gives 4-(trifluoromethyl)morpholine in excellent yields. 4-Formylmorpholine reacts with series of 2-alkyl-2-cyclohexen-1-ones in the presence of POCl3 to give the corresponding 3-alkyl-2-chloro-5,6-dihydrobenzaldehydes and allylic alcohols (by-product).