New Trifluoromethylated Imidazolidines, Oxazolidines and Thiazolidines Starting from 3-(1,1-Dihydroxy-2,2,2-trifluoroethyl)-1-methyl- tetrahydroazepin-2-one and α-(1,1-Dihydroxy-2,2,2-trifluoroethyl) -γ-butyrolactone.