Synthesis of phosphanes bearing 2-imino-1,3-thiazolidine ligands - X-ray analyses and NMR spectroscopy

Pseudo-ephedrine derived 2-imino-1,3-thiazolidine I reacts with tris(diethy lamino)phosphane by stepwise replacement of the diethylamino group to give the mono-, bis- and tris(imino)phosphanes 2, 3 and 4, respectively, of whic h 4 could be isolated in pure state. The analogous reaction with diethylami no-diphenylphosphane affords the imino-di-phenylphosphane 5. The iminophosp hanes react with sulfur or selenium to give the corresponding phosphorus(V) compounds. In contrast, the reaction of the iminophosphanes with oxygen is very slow; anhydrous trimethylamine N-oxide reacts in the melt with the ph osphanes to give the oxides 4(O) and 5(O). The molecular structures of 4(O) (in mixture with 4), 4(Se), 5(S) and 5(Se) were determined by X-ray analys is. In all cases the ring-sulfur and the phosphorus atoms are in cis-positi ons at the C=N bonds. The analogous solution structures were determined by H-1, C-13, N-15, P-31 and Se-77 NMR spectroscopy. In the case of the compou nds 5, 5(O), 5(S) and 5(Se) the isotope-induced chemical shifts 1 Delta N-1 4/15(P-31) were determined, using INEPT-HEED experiments.