p-Toluenesulfonic acid monohydrate → (R)-4-(3,4-dichlorobenzenesulfonyl)-3-(prop-2-ynyl)-3,4-dihydropyrazin-2(1H)-one

Participants

Reaction Conditions

Reaction Steps

A solution of (R)-2-(3,4-dichlorobenzenesulfonamido)-N-(2,2-dimethoxyethyl)pent-4-ynamide (36.7 g, 89.6 mmol) in 500 mL p-dioxane was treated with TsOH.H2O (5.11 g, 26.9 mmol). The reaction was heated to 60° C. for 7 h and then at 80° C. for 19 h. The mixture was cooled to room temperature and concentrated under reduced pressure. The residue was diluted with 400 mL EtOAc stirred with 400 mL 5% NaHCO3. The resulting precipitate was filtered and washed with H2O. The solid was suspended in hot EtOH and cooled to rt. The solid was collected by filtration, washed with EtOH and dried in vacuo to yield the title compound.

Provenance & Evidence