Synthesis of Phosphanes Bearing 2-Imino-1,3-thiazolidine Ligands - X-Ray Analyses and NMR Spectroscopy

Abstract

Pseudo-ephedrine derived 2-imino-1,3-thiazolidine 1 reacts with tris(diethylamino)phosphane by stepwise replacement of the diethylamino group to give the mono-, bisand tris(imino)phosphanes 2, 3 and 4, respectively, of which 4 could be isolated in pure state. The analogous reaction with diethylamino-diphenylphosphane affords the imino-diphenylphosphane 5. The iminophosphanes 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 phosphanes 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 analysis. In all cases the ring-sulfur and the phosphorus atoms are in cis-positions at the C=N bonds. The analogous solution structures were determined by 1 H, 13 C, 15 N, 31 P and 77 Se NMR spectroscopy. In the case of the compounds 5, 5(O), 5(S) and 5(Se) the isotope-induced chemical shifts 1 D 14/15 N( 31 P) were determined, using INEPT-HEED experiments.Synthese von Phosphanen mit dem 2-Imino-1,3-thiazolidin-Substituenten ± Ro È ntgenstrukturanalysen und NMR-Spektroskopie Inhaltsu È bersicht. 2-Imino-1,3-thiazolidin (1), ein Derivat des pseudo-Ephedrins, reagiert mit Tris(diethylamino)phosphan u È ber stufenweisen Ersatz der Diethylamino-Gruppe zu den Mono-, Bis-und Tris(imino)phosphanen 2, 3 und 4, von denen 4 rein isoliert werden konnte. Die analoge Reaktion mit Diethylamino-diphenylphosphan liefert das Imino-diphenylphosphan 5. Die Iminophosphane reagieren mit Schwefel oder Selen zu den entsprechenden Phosphor(V)-Verbindungen. Im Gegensatz dazu verla È uft die Reaktion der Iminophosphane mit Sauerstoff nur sehr langsam; wasserfreies Trimethylamin-N-oxid reagiert in der Schmelze mit den Phosphanen zu den Oxiden 4(O) und 5(O). Die Moleku È lstrukturen von 4(O) (in Mischung mit 4), 4(Se), 5(S) und 5(Se) wurden mittels Ro È ntgenstrukturanalyse bestimmt. In allen Fa È llen finden sich Ring-Schwefel-und Phosphoratome in cis-Stellung an der C=N-Bindung. Die analogen Strukturen in Lo È sung folgen aus den 1 H-, 13 C-, 15 N-, 31 P-und 77 -Se-NMR Spektren. Im Fall der Verbindungen 5, 5(O), 5(S) und 5(Se) gelang die Messung der Isotopen-induzierten chemischen Verschiebungen 1 D 14/15 N( 31 P) mittels INEPT-HEED-Experimenten.

Synthesis and characterization of the first phosphonic diamide containing thiazolyl groups: Structural properties and tautomeric equilibrium

“…Thus, intermolecular interactions can play a major role not only in determining the tautomeric species present in the solid-phase but also affecting the conformational behavior. It has been recognized that related 2-aminobenzothiazole derivatives are at the same time a base and a very reactive acid [48]. Interestingly the formation of ADAD-DADA type (A, acceptor site; D, donor site) centro-symmetric dimers is observed in the crystalline state.…”

Phosphorus heterocycles from 2‐(2‐hydroxyphenyl)‐1H‐benzimidazole

“…The bond length N1-P2 1.693 (2)Å has some double bond character, whereas P2-N4 is shorter (1.609 A, single bond P N is 1.77 A, [35]), this fact was attributed to some double bond character [37] which also explains the planar geometry at N4. The P2 O1 bond length 1.605Å is characteristic of a P O single bond in tetracoordinated compounds [36], whereas bond length P Se (2.0625Å) is a normal double bond [38].…”

“…The P E (E = S, Se) bonds have some electron withdrawing effect over the phenolic part of the ligand as is deduced from the shift to higher frequencies of C14 and the shielding of C11 ipso to oxygen. The value of the coupling constant 1 J ( 31 P, 13 C) for the ipso carbon of phenyl group in 30 and 31 increases with oxidation indicating the bigger electroattractor effect of P E [38].…”