Ammonia → tert-Butyl 4-amino-2-azaspiro[4.4]nonane-2-carboxylate

Reaction equation

O=[C:2]1[C:6]2([CH2:10][CH2:9][CH2:8][CH2:7]2)[CH2:5][N:4]([C:11]([O:13][C:14]([CH3:17])([CH3:16])[CH3:15])=[O:12])[CH2:3]1.[BH4-].[Na+].[NH3:20]>>[NH2:20][CH:2]1[C:6]2([CH2:10][CH2:9][CH2:8][CH2:7]2)[CH2:5][N:4]([C:11]([O:13][C:14]([CH3:17])([CH3:16])[CH3:15])=[O:12])[CH2:3]1

Participants

Reactant 3

HCID 222Ammonia

HCID 4311764Sodium borohydride

HCID 118390010Tert-butyl 4-oxo-2-azaspiro[4.4]nonane-2-carboxylate

Product 1

HCID 71305997tert-Butyl 4-amino-2-azaspiro[4.4]nonane-2-carboxylateYield 58%

Procedure

To a solution of tert-butyl 4-oxo-2-azaspiro[4.4]nonane-2-carboxylate (8.56 g, 35.77 mmol) in ammonia (7M in methanol, 100 mL) was added Ti(Oi-Pr)4 (22.37 g, 78.6 mmol) and the reaction mixture was stirred at rt overnight. Then NaBH4 (2.71 g, 71.54 mmol) was added portion-wise and the resulting mixture was stirred at rt for another 2 h and concentrated in vacuo. The residue was purified by silica gel column chromatography (DCM/MeOH (v/v)=10/1) to give the product as yellow oil (5 g, 58%).