(2R)-1-[(2-methylpropan-2-yl)oxycarbonyl]azetidine-2-carboxylic acid

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of 2M LiBH4 (200 ml, 400 mmol) in THF at 0° C. was added TMSCl (101 ml, 800 mmol) slowly. The mixture was warmed up to r.t and stirred at r.t. for 30 min. To the mixture at 0° C. was added a solution of (R)-1-(tert-butoxycarbonyl)azetidine-2-carboxylic acid (40 g, 200 mmol) in 200 ml THF with an additional funnel over 1 hour. The mixture was warmed up to r.t and stirred at r.t. for 2 hours. The mixture was cooled down to 0° C. and then treated with 32 mL MeOH followed by 40 mL H2O. After removal of THF, the residue was extracted with 300 mL EtOAc and washed with 300 mL brine. The organic layer was dried and concentrated to give (R)-tert-butyl 2-(hydroxymethyl)azetidine-1-carboxylate as a colorless oil (32.5 g, 87%). LRMS (M−100+H+) m/z 132.1. The mixture was warmed up The mixture was warmed up stirred at r.t. for 2 hours The mixture was cooled down to 0° C. After removal of THF the residue was extracted with 300 mL EtOAc washed with 300 mL brine The organic layer was dried concentrated