Trifluoroacetic acid → 1-(2-Propynyl)piperazine

Participants

Reaction Steps

To a flame-dried 25 mL round bottom flask under nitrogen was added 2.1 g of 4-Prop-2-ynyl-piperazine-1-carboxylic acid tert-butyl ester. To this solid was added 5 mL of 98% TFA in 1 mL portions. The solution turned wine red, bubbled and smoked. The additional portions of TFA were added when this activity subsided. After the third portion of TFA had been added only minimal bubbling occurred. The solution was allowed to stir under nitrogen at room temperature for an additional hour and evaporated under reduced pressure to yield the product as a thick red syrup. Assumed quantitative yield of 1.16 g. The residue was suspended in 20 mL dichloromethane and used immediately without further purification for the preparation of compounds JR4031, JR4033, and JR4035.

Provenance & Evidence