反应详情

温度

70 °C

To a solution of crude (1aS,5aR)-1,1,2-trimethyl-1,1a,5,5a-tetrahydro-3-thia-cyclopropa[a]pentalene-4-carboxylic acid ethyl ester (10.3 g, 41.2 mmol) in ethanol (200 mL) a solution of 2N aq. LiOH (300 mL) is added. The resulting mixture is stirred at 70° C. for 1 h, cooled to rt and diluted with water (250 mL). The aq. solution is extracted three times with DCM (125 mL) before it is acidified to pH 3 by adding citric acid. The acidified solution is extracted twice with DCM (2×250 mL). These second extracts are combined, dried over Na2SO4, filtered and evaporated to leave (1aS,5aR)-1,1,2-trimethyl-1,1a,5,5a-tetrahydro-3-thia-cyclopropa[a]pentalene-4-carboxylic acid (7.0 g) as a yellow solid. LC-MS: tR=0.95 min, [M+1]+=223.00. 1H NMR (CDCl3): δ3.04-2.92 (m, 1H), 2.83 (d, J=19.3 Hz, 1H), 2.39 (s, 3H), 1.91-1.87 (m, 2H), 1.13 (s, 3H), 0.73 (s, 3H).

1. temperaturecooled to rt
2. extractionThe aq. solution is extracted three times with DCM (125 mL) before it
3. additionby adding citric acid
4. extractionThe acidified solution is extracted twice with DCM (2×250 mL)
5. dry with materialdried over Na2SO4
6. filtrationfiltered
7. customevaporated