H. Gali et al., Facile ring-opening reactions of phthalimides as a new strategy to synthesize amide-functionalized phosphonates, primary phosphines, and bisphosphines, J ORG CHEM, 65(3), 2000, pp. 676-680
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.