[OH2:1].[C:2]1([CH3:12])[CH:7]=[CH:6][C:5](S(O)(=O)=O)=[CH:4][CH:3]=1.[C:13](=O)(O)[O-].[Na+]>C(Cl)Cl.COCOC>[CH3:13][CH2:3][C:4](=[O:1])[CH2:5][CH2:6][CH2:7][CH2:2][CH3:12]To a solution of 6(7)-hydroxy-2-methoxycarbonyl-8-azabicyclo(3.2.1)octane-3-one (18 g, 84.5 mmol) in 200 ml of CH2Cl2, 70 ml of dimethoxymethane was added, followed by (18 g, 93 mmol) of p-toluene sulfonic acid monohydrate. The round-bottom flask was fitted with a soxhiet extractor containing 3-4 A molecular sieves. The reaction mixture was heated to reflux with stirring until the starting material had disappeared (TLC). The mixture was cooled and treated with sat. sodium bicarbonate solution and extracted with CH2Cl2. The combined organics were dried over K2CO3 removed in vacuo and applied to column (silica gel, 10% Et3N, 30% EtOAc/hexane). 6-Methoxymethoxy-2-methoxy-carbonyl-8-azabicyclo(3.2.1))octane-3-one (2.2 g) was obtained as a yellow oil. Rf 0.3 (10% Et3N, 30% EtOAc in hexane).
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