p-Toluenesulfonic acid → HCID 19434123, compound

Participants

Reaction Steps

A mixture of the product from Step A (8.80 g, 26.3 mmol) and 4-toluenesulfonic acid (1.0 g) in acetone (250 mL) was stirred overnight at ambient temperature. Water (0.5 mL) was added and this mixture was stirred for 4 h followed by addition of a saturated aqueous solution of sodium bicarbonate (50 mL) and evaporation of the acetone. The aqueous mixture was extracted with ethyl acetate (2×200 mL) and the combined extracts were dried (MgSO4) and evaporated to give crude aldehyde which was dissolved in ethyl acetate (150 mL). DBN (0.5 g) was added and the mixture heated at reflux temperature for 2 h, cooled and washed with a saturated aqueous solution of sodium bicarbonate (50 mL). The ethyl acetate solution was dried (MgSO4) and evaporated to a residue which was purified by column chromatography (silica, 30 to 50% ethyl acetate/hexane) to give the desired product as a white solid (5.05 g, 70%).

Provenance & Evidence