Yield:-

Reaction Conditions:

Stage #1:tert-butyl 3-cyanoazetidine-1-carboxylate with n-butyllithium;diisopropylamine in tetrahydrofuran;hexane at -78; for 1 h;
Stage #2:1-Hydroxymethyl-1H-benzotriazole in tetrahydrofuran;hexane at -78; for 3 h;
Stage #3: with ammonium chloride in tetrahydrofuran;hexane;water

Steps:

24
Preparation Example 24 To a solution of N-isopropylpropan-2-amine (11.54 mL) in THF (50 mL) was added dropwise a solution of n-butyllithium in hexane (1.6 M, 51.45 mL) at -78°C. The reaction mixture was warmed to 0°C and then stirred for 30 minutes. The reaction mixture was cooled to -78°C again, and then a solution of tert-butyl 3-cyanoazetidine-1-carboxylate (5.0 g) in THF (30 mL) was added dropwise, followed by stirring at -78°C for 1 hour. To the reaction mixture was added dropwise a solution of 1H-benzotriazol-1-yl-methanol (8.19 g) in THF (20 mL) at -78°C, followed by stirring at -78°C for 3 hours. To the reaction mixture was added a saturated aqueous NH₄Cl solution (100 mL), followed by extraction with EtOAc (50 mL) three times. The organic layer was washed with brine, dried over MgSO₄, and then concentrated under reduced pressure. The residue was purified by silica gel column chromatography (automatic purification device, hexane:EtOAc=100:0 to 50:50) to obtain tert-butyl 3-cyan-3-(hydroxymethyl)azetidine-1-carboxylate (5.68 g) as a white solid.

References:

Astellas Pharma Inc. EP2354134, 2011, A1 Location in patent:Page/Page column 23-24