We attempted to synthesize diethyl (I-methyl-2-phthaErnidoethy1) phosphonate (14a) in a Miehaelis-Beeker reaction using diethyl sodiophosphonate (13) and the tosylate 12a of (2- hydroxypropy1) phthalimide as starting materials. Instead of TsO substitution in 1Za by the nucleophile 13, the carbonyl C-atom of the phthalimido moiety was attacked by 13, followed by an intramolecular nucleophilic substitution at C (2) of the side chain leading to the ( ...