Benzyl 3-(2-(tert-butyldimethylsilyloxy)-1-hydroxyethyl)phenylcarbamate (4 g) was dissolved in dry DCM (80 mL) and cooled to 0° C. under an argon atmosphere. Triethylamine (5 g) was added, followed by mesyl chloride (3.42 g) added drop-wise over a period of 2 hours. The reaction temp was maintained at 0° C. for further 2 hours. The reaction was quenched by addition of water, extracted into DCM and concentrated under vacuum at a temperature below 25° C. The crude product (3.5 g) was unstable and was used for next step as soon as possible.
