The investigations of the reactions of hexachlorocyclotriphosphazene with N-alkyl-2-thiophenylmethylethanediamines

In this study, Schiff bases were obtained by reacting 2-thiophenecarboxaldehyde with N-methyl-1,2-diaminoethane, N-ethyl-1,2-diaminoethane and N-methyl-1,3-diaminopropane in ethanol, and diamine ligands (1-3) were obtained from the reduction of these Schiff bases with NaBH4. Regioselectively, tetrachloro-2-thiophenylmethylspirocyclotriphosphazenes (4-6) were obtained by the reaction of the ligands with hexachlorocyclotriphosphazatriene, N3P3Cl6. Fully substituted cyclotriphosphazenes (7-18) were synthesized from the reactions of tetrachloro-2-thiophenylmethylspirocyclotriphosphazenes (4 and 5) with piperidine and 1,4-dioxa-8-azaspiro[4.5]decane, benzylamine, 1-(2-aminoethyl) piperidine, butylamine and 7- hydroxycoumarin. In addition, the reactions of partially substituted trimeric phosphazenes (4 and 5) with 7-hydroxy coumarin at a 1:2 mole ratio gave partially coumarin substituted 2- thiophenylmethylspirocyclotriphosphazenes (19-26) in dry THF. The new compounds were separated by column chromatography and preparative thin-layer chromatography (TLC). The structures of the phosphazenes were elucidated by elemental analysis, mass (ESI-MS), FTIR, one-dimension (1H, 13C- and 31P-NMR) and two-dimension (HSQC) spectroscopy techniques. The solid-state structure of 8 was characterized by the X-ray diffraction technique. Compounds 19 and 23 contain one chiral phosphorus atom; and therefore they are a racemic mixture (R/S). Compounds 20 and 24 have two equivalents of stereogenic phosphorus atoms. It was determined from the 31P NMR spectrum that the cis and trans isomer of 20 were a mixture (RR/RS or SS/SR diastereomer mixture), and 24 was trans-non-geminal (RR/SS enantiomeric mixture, raceme). Compounds 21, 22, 25 and 26 have two non-equivalent stereogenic phosphorus atoms and are present as a mixture of diastereomers.