p-Toluenesulfonic acid → 4,5-dihydro-7-oxo-8-phenyl-7H-thieno[2,3-a]quinolizine-10-carboxaldehyde

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Reaction Steps

A mixture of 0.855 g of 5,6-dihydro-3-hydroxy-2-phenylthiazolo[3,2-a]thieno[2,3-c]pyridinium hydroxide (internal salt) and 0.65 ml of 3,3-diethoxypropyne in 30 ml of cyclohexanone was stirred with a few crystals of p-toluenesulfonic acid at 130° for 3 hours under an inert gas and then concentrated in vacuo. The residue was taken up in ethyl acetate, washed with 10 percent potassium bicarbonate soluttion and saturated sodium chloride solution, dried over magnesium sulfate, concentrated and chromatographed on silica gel with toluene/acetonitrile (19:1). By crystallization from dioxane, there is obtained 4,5-dihydro-7-oxo-8-phenyl -7H-thieno[2,3-a]quinolizine-10-carboxaldehyde of m p. 213°-215°.

Provenance & Evidence