Acetic Acid → 9-(Tert-butoxycarbonyl)-4-(2,2,2-trifluoroethyl)-1-oxa-4,9-diazaspiro[5.5]undecane-2-carboxylic acid

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Reaction Steps

9-Tert-butyl 2-methyl 4-(2,2,2-trifluoroethyl)-1-oxa-4,9-diazaspiro[5.5]undecane-2,9-dicarboxylate (197 mg, 0.48 mmol) was dissolved in MeOH (1 mL)/H2O (1 mL), followed by the addition of LiOH (46 mg, 1.92 mmol) and the reaction mixture was stirred for 2 hours at room temperature. The solvent was removed in vacuo and the residue was dissolved in water (2 mL) and cooled to 0° C., then acetic acid (115 mg, 109 μL, 1.92 mmol) was added dropwise (pH=5). The product was partitioned between EtOAc/water, the layers were separated and the aqueous layer was extracted once more with EtOAc. The organics were dried over Na2SO4, filtered and concentrated in vacuo to yield an oil. The oil was co-evaporated twice with toluene and dried under high vacuum to yield 9-(tert-butoxycarbonyl)-4-(2,2,2-trifluoroethyl)-1-oxa-4,9-diazaspiro[5.5]undecane-2-carboxylic acid (142 mg, 77%) as a white foam. ESI-MS m/z calc. 382.4. found 383.5 (M+1)+; Retention time: 1.58 minutes (3 min run).

Provenance & Evidence