Facile ring-opening reactions of phthalimides as a new strategy to synthesize amide-functionalized phosphonates, primary phosphines, and bisphosphines

The nucleophile-assisted ring-opening reaction of phthalimides 1 has been s tudied. The reaction of phthalimides 1 with 0.5 equiv of hydrazine produced the novel bisphosphonates 2 in near quantitative yields whereas with 10-fo ld excess of hydrazine, diethyl aminoalkylphosphonates 3 was formed in 75% yields. The reaction of phthalimide Ib with 3-(aminopropyl)phosphine result ed in a novel compound 4a containing a P-III hydride and a P-V phosphonate within the same molecule. In addition, the reaction of Ib with 2-aminoethan ol and 2-aminoethanethiol resulted in the formation of new phosphonates 4b, c. The reaction of bisphosphonates 2 with LiAlH4 in THF at 0 degrees C sele ctively reduced the phosphonate groups producing corresponding air-stable p rimary bisphosphines 6 in 80% yields. Further, the formylation of bisphosph ines 6 under very mild conditions using 37% aqueous formaldehyde produced t he corresponding novel water-soluble bisphosphine chelating agents 7 in nea r quantitative yields. All the new compounds have been characterized by H-1 , C-13, P-31 NMR, IR spectroscopy and mass spectrometry.