p-Toluenesulfonic acid → 1-Cyclohexyl-6-(3-formyl-1-pyrrolyl)-7-nitro-2,3(1H,4H)-quinoxalinedione

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Reaction Steps

4 g (13 mmol) of the product 37b, 2.3 g (14 mmol) of 3-formyl-2,5-dimethoxytetrahydrofuran and a spatula tip of 4-toluenesulfonic acid in 200 ml of dimethylformamide/toluene (1:1) were refluxed with a water trap. After the reaction was complete (TLC check), the mixture was concentrated under reduced pressure, and the residue was partitioned between ethyl acetate and water. The organic phase was dried and concentrated under reduced pressure. This residue was purified by chromatography on silica gel (mobile phase: toluene/acetone/glacial acetic acid=40/20/1) to yield 1.1 g (22%) of the product.

Provenance & Evidence