Isopropyl acetate (300 mL) was charged into a 1000 ml 3-neck flask and cooled to −10˜−5° C. Sulfurisocyanatidic chloride (44.5 mL) was added at −5˜10° C. followed by the addition of phenylmethanol (50.5 mL) in isopropyl acetate (60 mL) at −5˜10° C. over 60 minutes. The mixture reacted at −5˜10° C. and was monitored by HPLC until the content of benzyl alcohol was <2% (after 1 hour at 0° C.). A mixture of acetonitrile (300 mL), 3-methylazetidine hydrochloride (50 g) (Intermediate C, either commercially available or prepared as set out below) and triethylamine (162 mL) was stirred in a 2000 mL 3-neck flask and to this was added the solution of the intermediate benzyl chlorosulfonylcarbamate in isopropyl acetate (360 mL) dropwise at <−5° C. over 90 minutes. The mixture was allowed to warm to RT overnight. The reaction was quenched with acetic acid and pH was adjusted to 4˜5. The mixture was separated and the aqueous phase was washed with isopropyl acetate (500 ml) and then separated. The organic phase was combined and washed with 10% brine (2×120 ml), dried with anhydrous magnesium sulphate, filtered and the filter cake washed with isopropyl acetate (30 ml) and filtered to afford the sub-title product (145 g) as a red oil.
