Synthesis and NMR spectroscopic study of new 5-methylfuryl-containing Schiff bases and related bis(aminophosphonates)

The synthesis of three novel 5-methylfuryl-containing Schiff bases: N,N'-bis(5-methylfurfurylidene)-4,4'-diaminodiphenylmethane, N,N'bis(5-methylfurfurylidene)-1,4-phenylenediamine, and N,N'-bis(5-methylfurfurylidene)benzidine and the corresponding bis(aminophosphonates) derived from them, 4,4'-bis{N-methyl(diethoxy-phosponyl)-1-[(5-methyl)-2-furyl]}diaminodiphenylmethane, 1,4-bis {N-methyl(diethoxyphosphonyl)-1-[(5-methyl)-2-furyl]}diaminobenzene, and bis{N-methyl(diethoxyphosphonyl)-1-[(5-methyl)-2-furyl]}-benzidine, is reported. The compounds have been characterized by elemental analysis, TLC, JR, and NMR (H-1, C-13, and P-31) spectra. For comparison, new C-13 and P-31 NMR data of three furyl-containing analogues of the above bis(aminophosphonates) are also regarded. The NMR studies of the two series of bis(aminophosphonates) reveal the presence of one diastereomer (meso or racemic form).