PHOSPHORORGANISCHE VERBINDUNGEN 991VERSUCHE ZUR AUFKLÄRUNG DER O-SELEKTIVITÄT VON VERBINDUNGEN MIT DER P(O)F-GRUPPE

Abstract

Abstract The mechanism of the reaction of phosphoryl fluoride ( P(O)F) with alcohols in the presence of an amine is fundamentally different from the reaction of phosphoryl chlorides ( P(O)Cl) with primary or secondary amines. The following observations strongly support this proposal: 1. 1H-NMR-, 31P-NMR- and 19F-NMR-spectroscopic investigations show that methyl-phenyl-phosphinicacid-fluoride and n-butylamine form a thermolabile adduct, which yields the methyl-phenyl-phosphinicacid-amide only very slowly. 2. The rate of the reaction of methyl-phenyl-phosphinicacid-fluoride with ethanol is independent of the basicity of the amine but very sensitive to steric factors. Imidazole (which is only a weak base) is surprisingly active. 3. The application of optically active amines as bases in the reaction of racemic methyl-phenyl-phosphinicacid-fluoride with methanol leads to partially optically active methyl-phenyl-phosphinicacid-methylester. This observation proves that the amines are incorporated in the intermed...