Facile Ring-Opening Reactions of Phthalimides as a New Strategy to Synthesize Amide-Functionalized Phosphonates, Primary Phosphines, and Bisphosphines

Abstract

The nucleophile-assisted ring-opening reaction of phthalimides 1 has been studied. The reaction of phthalimides 1 with 0.5 equiv of hydrazine produced the novel bisphosphonates 2 in near quantitative yields whereas with 10-fold excess of hydrazine, diethyl aminoalkylphosphonates 3 was formed in 75% yields. The reaction of phthalimide 1b with 3-(aminopropyl)phosphine resulted in a novel compound 4a containing a PIII hydride and a PV phosphonate within the same molecule. In addition, the reaction of 1b with 2-aminoethanol and 2-aminoethanethiol resulted in the formation of new phosphonates 4b,c. The reaction of bisphosphonates 2 with LiAlH4 in THF at 0 °C selectively reduced the phosphonate groups producing corresponding air-stable primary bisphosphines 6 in 80% yields. Further, the formylation of bisphosphines 6 under very mild conditions using 37% aqueous formaldehyde produced the corresponding novel water-soluble bisphosphine chelating agents 7 in near quantitative yields. All the new compounds have been characterized by 1H, 13C, 31P NMR, IR spectroscopy and mass spectrometry.