tert-Butyl 4-oxo-3,4-dihydroquinoline-1(2H)-carboxylate → tert-butyl 4-methylene-3,4-dihydroquinoline-1(2H)-carboxylate

Participants

Reaction Steps

A solution of methyltriphenylphosphonium bromide (1.92 g, 5.38 mmol, 1.1 equiv; [CAS RN 1779-49-3]) and potassium tert-butoxide (0.60 g, 5.38 mmol, 1.1 equiv; [CAS RN 865-47-4]) in toluene (20 mL) were heated to reflux. After 1 h, 4-oxo-3,4-dihydro-2H-quinoline-1-carboxylic acid tert-butyl ester (1.21 g, 4.89 mmol, 1.0 equiv; [CAS RN 179898-00-1]), dissolved in toluene (10 mL), was added and heating continued for one additional hour. The reaction mixture was extraction from a sat. solution of NH4Cl (100 mL) with ethyl acetate (3×50 mL) and the combined organic phases dried over MgSO4. Purification by silica column chromatography using a MPLC system (CombiFlash Companion, Isco Inc.) eluting with a gradient of heptane/ethyl acetate afforded 0.87 g (73%) of the title compound as a colorless oil. MS (ISP): 246.4 [M+H]+.

Provenance & Evidence