A New and Convenient Synthesis of 1-Benzyloxyaminoalkyl Phosphonic and Phosphinic Acids From Oximes

New strategy for the synthesis of functionalized phosphonic acids

“…After 6 hours, the imidoyl chloride disappeared completely, and the mixture was worked up to give the iminophosphonate in 95% yield. Signals in the 31 P NMR spectra at d ‫ס‬ 7.37 (q, J ‫ס‬ 9.2 Hz) definitely revealed the formation of the Arbuzov reaction product. The subsequent reduction was achieved by treatment with NaBH 3 CN as indicated by the 31 P NMR resonance at d ‫ס‬ 15.2 (q, J ‫ס‬ 8.7 Hz), much downfield from that of the iminophosphonate, because the phosphonate moiety in the product is linked to an sp 3 -hybridized carbon, while in the iminophosphonate, it is linked to an sp 2 carbon.…”

“…A number of syntheses have been developed to provide a convenient route to this class of compounds, including the controlled reduction of 1-nitroalkylphosphonates with zinc and ammonium chloride [28], the addition of a dialkyl phosphite to a 1-oxoaldoxime at an elevated temperature [29], the nucleophilic addition of a lithium or potassium dialkyl phosphite to N-glycosylnitrone followed by glycoside cleavage and hydrolysis [30], and the condensation of 1-(benzyloxyamino)alkylphosphonic acid with an O-alkylisourea, followed by treatment with boron tris(trifluoroacetate) [31]. These methods are, New Strategy for the Synthesis of Functionalized Phosphonic Acids 109 SCHEME 7 SCHEME 8 SCHEME 9 SCHEME 10 however, limited by their narrow scope, other competitive reactions, and relatively inaccessible starting materials.…”