Ionic liquids/H2O systems for the reaction of epoxides with NaN3: a new protocol for the synthesis of 2-azidoalcohols

Oxiranes undergo ring opening rapidly with sodium azide in a [bmim]BF4/H2O or [bmim]PF6/H2O (2:1) solvent system, under mild and neutral reaction conditions to afford the corresponding 2-azidoalcohols in high to quantitative yields. The remarkable features of this procedure are improved yields, enhanced reaction rates, high regioselectivity and ease of recyclability of ionic liquids (ILs). The recovered ionic liquid can be reused for four to five times but with gradual decrease in activity.