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

A solution of tert-butyl 4-(2-isopropylthiazole-4-carbonyl)-1-oxa-4,9-diazaspiro[5.5]undecane-9-carboxylate (example 22, step a) (2.3 g) in a mixture of dichloromethane (40 mL) and trifluoroacetic acid (10 mL) was allowed to stand at 20° C. for 30 minutes. Toluene (50 mL) was added and the solvents were evaporated, then this process was repeated with further toluene (50 mL). The residue was triturated with ether. The gum was then dissolved in acetonitrile and the solvent evaporated to afford the subtitled compound. Yield 1.64 g.