Hydrolysis of Cyclic Phosphites/Phosphoramidites and Its Inhibition-Reversible Cyclization of Acyclic Phosphonate Salts to Cyclic Phosphites

Hydrolysis of cyclic phosphites/phosphoramidites (OCH2CRR‘CH2O)PX [X = OPh (1), NMe2 (2)] in the presence of
intentionally added water is effectively inhibited by using simple
additives such as KF, K2CO3, Et3N, and molecular sieves.
Among these, K2CO3 gave the best results. Cyclic H-phosphonates (OCH2CRR‘CH2O)P(O)H (3), which are the tautomeric
forms of the phosphites (OCH2CRR‘CH2O)P(OH), undergo
facile hydrolysis in the presence of aqueous amines to give the
acyclic phosphonate salts [H2NMe2]+[(HOCH2CRR‘CH2O)P(O)(H)(O-)] (4) that can be reverted back to 3 upon simple heating.
Interestingly, competitive reactions of (OCH2CRR‘CH2O)PX
[X = Cl (I−III), NMe2 (2)] with phenol and water in the
presence of K2CO3 led only to the phenoxy derivatives and not
to the hydrolysis products.