A useful magnesium reagent for the preparation of 1,1-difluoro-2-hydroxyphosphonates from diethyl bromodifluoromethylphosphonate via a metal—halogen exchange reaction

Rachel Waschbüsch (1) , Mohammad Samadi (1) , Philippe Savignac (1)

1 DCPH - Laboratoire Hétéroéléments et Coordination

When (EtO) 2 P(O)CF 2 Br (1) is treated with isopropylmagnesium chloride in THF at low temperature it gives a magnesium species (2) which undergoes reactions with strong electrophiles (HCl, TMSCl, halogens, aldehydes and ketones). The formation of products strongly depends on the reaction conditions. With 1.5 equivalents of (2) between-78°C and 0°C, a conversion of more than 90% of aldehydes and ketones into 2-hydroxyphosphonates (7) and (8) can be achieved. These compounds (7) and (8) in the presence of base (NaH, LDA) are rearranged into 2,2-difluoroethylphosphates without concomitant formation of 1,1-difluoroolefines.

Mots clés: Isopropylmagnesium chloride; Metal-halogen exchange; Bromodifluorophosphonate; 1-1-Difluoro-2-hydroxyphosphonate

Domaines: Chimie organique

Rachel Waschbüsch, Mohammad Samadi, Philippe Savignac. A useful magnesium reagent for the preparation of 1,1-difluoro-2-hydroxyphosphonates from diethyl bromodifluoromethylphosphonate via a metal—halogen exchange reaction. Journal of Organometallic Chemistry, 1997, 529 (1-2), pp.267-278. ⟨10.1016/S0022-328X(96)06541-2⟩. ⟨hal-03166507⟩