2-Methylindolizine → (5E)-4-methylidene-5-{(2E)-2-[(2-methylindolizin-3-yl)carbonyl]but-2-en-1-ylidene}-2-phenyl-4,5-dihydro-6H-1,3-oxazin-6-one

Participants

Reaction Steps

A solution of 2-methylindolizine (11.5 g; 87.7 mmol) in 35 mL of THF is added dropwise to a suspension of (2E)-2-[(E)-(4-methylidene-6-oxo-2-phenyl-4H-1,3-oxazin-5(6H)-ylidene)methyl]but-2-enoyl chloride (25 g; 87.7 mmol) in 140 mL of THF at 0° C. under nitrogen. After 18 h of stirring at ambient temperature, the reaction medium is diluted in ethyl acetate, and the solution is washed with a saturated aqueous solution of sodium hydrogen carbonate, dried over sodium sulphate and concentrated to dryness. The residue obtained is purified by flash chromatography on silica (DCM) to give 22.75 g (69%) of a yellow powder.

Provenance & Evidence