Trifluoroacetic acid → (2-Isopropylthiazol-4-yl)(1-oxa-4,9-diazaspiro[5.5]undecan-4-yl)methanone trifluoroacetate

Participants

Reaction Steps

To a solution of tert-butyl 4-(2-isopropylthiazole-4-carbonyl)-1-oxa-4,9-diazaspiro[5.5]undecane-9-carboxylate (limiting reagent) (step a) in DCM (5 volumes) was added trifluoroacetic acid (13.4 molar equivalents) in portions at 10-15° C. The solution was allowed to warm to ambient and stirred for 16 hr. Solvent was evaporated and the residue was dissolved in diethyl ether (10 volumes). The solution was cooled in ice and scratched to give precipitation; the slurry was stirred at 0°-10° C. for 0.5 hr then filtered cold. The cake was washed with diethyl ether (5 volumes) and dried in vacuo at 35° C. to give a beige coloured powder. Yield: 91% of theoretical.

Provenance & Evidence