Carbon Dioxide → (1R,5R)-3,5,8,8-Tetramethyl-2,4-dioxo-3-azabicyclo[3.2.1]octane-1-carboxylic acid

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

To a solution of step 2 intermediate (2 g, 10.2 mmol) in THF maintained at −95° C. under N2 atmosphere, 1.2N Sec.BuLi in cyclohexane (9.5 mL, 13.3 mmol) was added. After stirring for 15 min at −95° C., small pieces of dry ice (2 g) were added and the reaction mixture was kept at this temperature for 1 h before quenching with water (3 mL). The reaction mixture was allowed to warm to room temperature. To this 5% NaHCO3 solution (100 mL) and diethyl ether (50 mL) was added, the aqueous layer was separated and acidified with KHSO4 to pH 2. This was extracted again with diethyl ether, washed with brine, dried with anhydrous Na2SO4 and concentrated. (1.85 g). 1H NMR (400 MHz, CDCl3) δ ppm: 1.0 (s, 3H), 1.1 (s, 3H), 1.26 (s, 3H), 1.88-1.98 (m, 2H), 2.64-2.72 (m, 1H), 2.8 (m, 1H), 3.13 (s, 3H). m/z (M−H): 238.

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