General Procedure A. Alcohol/diol (1.0 eq.) was dissolved in DMF (2.4 mL/mmol) under N2 and cooled to 0°C. 60% NaH in paraffin oil (1.2 -4.0 eq.) was carefully added and the flask was left to stir at 0°C for 30 min. A solution of mesylate (1.0 -3.0 eq.) in DMF (0.5 -0.8 mL/mmol) was then added to the flask dropwise and the reaction was left to stir at 60°C for 16 h. The mixture was then filtered through PTFE filters or celite and concentrated in vacuo and purified.