Dimethylformamide dimethyl acetal → (2e)-1-(1-Acetyl-2,3-dihydro-1h-indol-5-yl)-3-(dimethylamino)prop-2-en-1-one

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Reaction Conditions

Reaction Steps

A mixture of 1-(1-acetyl-2,3-dihydro-1H-indol-5-yl)ethanone (6.0 g) and N,N-dimethylformamide dimethylacetal (14.2 g) was refluxed at 110° C. for 4 hours and evaporated in vacuo. The residue was triturated with diisopropylether, collected by filtration, and dried in vacuo to afford crude (2E)-1-(1-acetyl-2,3-dihydro-1H-indol-5-yl)-3-(dimethylamino)prop-2-en-1-one (7.4 g). To a solution of crude product in methanol (100 mL) were added guanidine hydrochloride (3.56 g) and potassium tert-butoxide (3.86 g) and the mixture was stirred at 100° C. for 3 hours.

Provenance & Evidence