C[O:2][C:3]([C:5]1([CH2:20][CH2:21][CH3:22])[CH2:11][CH2:10][CH:9]2[N:12]([C:13]([O:15][C:16]([CH3:19])([CH3:18])[CH3:17])=[O:14])[CH:6]1[CH2:7][CH2:8]2)=O.[H-].[Al+3].[Li+].[H-].[H-].[H-].C(C(C(C([O-])=O)O)O)([O-])=O.[Na+].[K+]>O1CCCC1>[C:16]([O:15][C:13]([N:12]1[CH:9]2[CH2:8][CH2:7][CH:6]1[C:5]([CH2:3][OH:2])([CH2:20][CH2:21][CH3:22])[CH2:11][CH2:10]2)=[O:14])([CH3:18])([CH3:19])[CH3:17]2-Propyl-8-aza-bicyclo[3.2.1]octane-2,8-dicarboxylic acid 8-tert-butyl ester 2-methyl ester (mixture of endo and exo isomers from Step 6, 0.98 g, 3.1 mmol) was dissolved in tetrahydrofuran (15 mL), and the resulting mixture was cooled to 0° C. A solution of lithium aluminum hydride in tetrahydrofuran (1 M, 3.3 mL, 3.3 mmol) in tetrahydrofuran was added dropwise over 10 minutes, and stirring was continued at 0° C. for 1.5 hours. A saturated aqueous solution of potassium sodium tartrate (10 mL) was added, and the mixture was warmed to room temperature and stirred for 15 hours. Additional saturated aqueous solution of potassium sodium tartrate (10 mL) was added, and the mixture was extracted with ethyl acetate. The combined organic extracts were washed with water and brine, dried over sodium sulfate, filtered, and concentrated under reduced pressure. The residue was purified by flash chromatography (silica gel, ethyl acetate/hexane) to provide 2-hydroxymethyl-2-propyl-8-azabicyclo[3.2.1]octane-8-carboxylic acid tert-butyl ester as a separable mixture of endo and exo isomers, both as colorless oils (0.68 g and 0.17 g, 76% and 19% yield, respectively).
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