Simple Route to Adducts of (Amino)(aryl)carbene with Phosphorus Pentafluoride

The tetramethyl ester of (hydroxy)(phenyl)methylenebis(phosphonic acid) reacts with morpholinosulfur trifluoride (MOST) to provide, along with the expected product of the substitution of a hydroxy group by fluorine, the adduct of (morpholino)(phenyl)carbene with PF5, compound 3a. Fluorination of dimethyl α-aroylphosphonates with MOST yields adducts of (amino)(aryl)carbene with PF5 (p-XC6H4)(Morph)C:PF5 [3a–f, where Morph is morpholyl, X = H (a), Me (b), OEt (c), F (d), Cl (e), CF3 (f)] as the major reaction products. The reaction mechanism proposed is based on experimental data and DFT calculations. The structure of adduct 3a was determined by X-ray studies. Hydrolysis of compounds 3e and 3f, bearing substituents Cl and CF3 on the phenyl ring, respectively, yields previously unknown benzoylpentafluorophosphates [p-XC6H4–C(=O)PF5]–MorphH+.