(4aS)-4aα,5,5aα,6,6aα,6b,7,7aβ-Octahydro-3,6bβ-dimethyl-5-methylenecycloprop[2,3]indeno[5,6-b]furan-2(4H)-one synthesis

Yield:70578-36-8 37%

Reaction Conditions:

with 3,5-dimethyl-1H-pyrazole;chromium(VI) oxide in dichloromethane at 0; for 13 h;Inert atmosphere;Reflux;

Steps:

4.8 (+)-Sarcandralactone A (1)

To a cooled (0 °C) solution of alkene 10 (20 mg, 0.081 mmol) in DCM (10 mL) were successively added CrO₃ (41 mg, 0.41 mmol) and 3,5-dimethylpyrazole (78 mg, 0.82 mmol). After being stirred at 0 °C for another 1 h, to the mixture was added Celite and heated to reflux for 12 h with an oil bath. After cooling to room temperature, the mixture was filtered through a silica gel pad and washed with Et₂O. The filtrate was concentrated under reduced pressure. The residue was purified by flash chromatography (Hexane/EtOAc=150:1 to 50:1 to 20:1) to afford lactone 12 (7 mg, 37%) and alkene 10 (9 mg, 45%).

References:

Qian, Shan;Zhao, Gang [Tetrahedron,2013,vol. 69,# 52,p. 11169 - 11173]