Hydrochloric Acid → HCID 20550582, compound

Participants

Reaction Conditions

Reaction Steps

110 ml. of 1 N sodium hydroxide were added dropwise over 30 minutes to a mixture of 26.95 g. (10.2 mmol) of crude 3-acetamido-5-(2-amino-4-methylphenyl)-2H-pyran-2-one in 200 ml. of tetrahydrofuran and 200 ml. of water under a nitrogen atmosphere. The resulting dark suspension was stirred for 30 minutes. 110 ml. of 1 N hydrochloric acid were added dropwise to the dark suspension. After removal of the tetrahydrofuran in vacuo and adjustment to pH 3, the dark suspension was cooled to 5° C., and filtered. The filter cake (21.1 g.) was dissolved in 1100 ml. of boiling methanol, treated with 2.0 g. of charcoal for 10 minutes and filtered through a bed of diatomaceous earth (which was washed with 200 ml. of hot methanol). The filtrate was concentrated to about 750 ml.; 150 ml. of water were added portionwise thereto; and the resulting solution was allowed to crystallize. A total of 16.1 g. (61%) of (E)-α-acetamido-6-methylindole-3-acrylic acid (mp 204.5-206° C.) was obtained in two crops.

Provenance & Evidence