The reaction of chlorophosphates with strong bases: synthesis and characterization of the phosphonate salts

Abstract

The reaction of (OCH₂CMe₂CH₂O)P(O)Cl (1)with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) afforded the phosphonate salt [(OCH₂CMe₂CH₂O)P(O)(DBU)]⁺[Cl] (3)^-; the X ray structure of this compound as a hydrate shows that the C-6 (labeled as Cl in Fig.1) of the DBU is connected to the phosphorus. In an analogous manner the eight-membered ring compound {CH₂(4-Me-2-t-Bu-C₆H₂O)₂}P(O)Cl (2) also afforded a phosphonate salt along with the pyrophosphate [{CH₂(4-Me-2-t-Bu-C₆H₂O)₂}P(O)]₂O (5). By contrast, in the reaction of 1 with 1,5-Diazabicyclo[4.3.0]non-5-ene (DBN), N-methyl imidazole or 4-dimethylaminopyridine no phosphonate salt was observed; the pyrophosphate was found to be the end product and could be isolated.