Tetraisopropyl methylenediphosphonate → Dihydro-1-pyrindine-6,6-diphosphonic acid tetraethyl ester

Participants

Reaction Steps

To an ice bath chilled solution of 35% potassium hydride in mineral oil (5.2 g; 0.045 moles) stirring under argon in 70 ml of DMSO (dry) is added a solution of tetraisopropylmethanediphosphonate (7.82 g; 0.023 moles) in 30 ml of DMSO. On completion of a dropwise addition, the resulting solution is stirred at room temperature for one hour. A solution of 2,3-bis(chloromethyl)pyridine (4.0 g; 0.023 mole) (crude product as isolated by K. Tsuda et.al., Chem Pharm Bull., 1, (1953), 142) in 15 ml of DMSO is slowly added and the reaction mixture is then heated at 90° C. for 1 hour. After cooling, the DMSO is removed under vacuum. 2.1 g (21%) of the desired product is purified via flash chromatography using a 5-15% ethanol in methylene chloride gradient on silica gel.

Provenance & Evidence