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

Abstract

Hydrolysis of cyclic phosphites/phosphoramidites (OCH2- CRR′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′CH 2O)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 K 2CO3 led only to the phenoxy derivatives and not to the hydrolysis products.