Yield:374794-94-2 89%

Reaction Conditions:

with trifluoroacetic acid in dichloromethane at 20;

Steps:

18.v (v) 2,2-DIMETHYL-1-OXA-8-AZASPIRO [4.5] decane

Trifluoroacetic acid (10ML) was added to a solution of 1, 1-dimethylethyl 4-hydroxy-4- (3-hydroxy-3-methylbut-1-yl)-1-piperidinecarboxylate (from step (iv) above; 3.9g, 13.57mmol) in dichloromethane (10ML) and the mixture was stirred at room temperature overnight. The solvent was evaporated under reduced pressure and the residue was purified by flash column chromatography on silica gel, eluting with CH2Cl2/MeOH/NH3 (Aq. ) (90: 10: 1) to give the title compound (2.04g, 89%). 1H NMR (400MHZ, CDC13): 8 3.27-3. 17 (4H, M), 1.95-1. 82 (6H, m), 1.70 (2H, d, J 13.4Hz), 1.22 (6H, s); m/z (ES+) 170 (M+1).

References:

WO2004/78750,2004,A1 Location in patent:Page 80-81