Synthesis and conformational analysis of 6-[N,N-bis(dihydroxyphosphorylmethyl)amino]methyl-2-hydroxy-2-oxido-1,4,2-oxazaphosphorinane-4-methylphosphonic acid by NMR spectroscopy

Abstract

The Kabachnik—Fields methylphosphorylation of 1,3-diaminopropan-2-ol affords a mixture of 1,3-diamino-2-hydroxypropane-N,N,N′,N′-tetrakismethylphosphonic acid and its intramolecular cyclic ester. Subsequent heating of this mixture led to the thermal dehydration of the acid with the 1,4,2-oxazaphosphorinane ring closure and the formation of 6-[N,N-bis(dihydroxyphosphorylmethyl)amino]methyl-2-hydroxy-2-oxido-1,4,2-oxazaphosphorinane4-methylphosphonic acid. A predominant chair conformation of the formed six-membered heterocycle was inferred from the data of 2D homonuclear (¹H, ¹H; J-resolved) and heteronuclear (¹H, ¹³C; HSQC, HMBC) NMR correlation spectra.