Triethylamine → (1R,3aS,5aR,5bR,7aR,11aR,11bR,13bR)-5a,5b,8,8,11a-pentamethyl-9-oxo-1-(prop-1-en-2-yl)icosahydro-1H-cyclopenta[a]chrysene-3a-carbaldehyde

Participants

Reaction Steps

To a 2M solution of oxalyl chloride (47.0 mL, 94 mmol) in CH2Cl2, was added a solution of DMSO (13.7 mL, 192 mmol) in CH2Cl2 (20 mL) dropwise at −15° C. After 5 min, a solution of (1R,3aS,5aR,5bR,7aR,9S,11aR,11bR,13bR)-3a-(hydroxymethyl)-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)icosahydro-1H-cyclopenta[a]chrysen-9-ol (4.43 g, 10.01 mmol) in a mixture of DMSO (30 mL) and CH2Cl2 (50 mL) was added at −15° C. Triethylamine (56 mL) was added 15 minutes later and the stirring was continued for another 10 min. The reaction mixture was allowed to warm up to RT. The reaction was quenched by addition of water (100 mL), and the reaction mixture was extracted with CH2Cl2 (70 mL×3). The combined organic layers were washed with brine (30 mL×3), dried over MgSO4, filtered and concentrated. The crude material was purified using silica gel chromatography eluted with a mixture of ethyl acetate and hexanes, to give the product as a solid (3.3 g 75%). LCMS: m/e 461.15 (M+Na)+, 2.91 min (method 2).

Provenance & Evidence