[OH:1][C:2]1([CH:8]([C:12]2[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=2)C(O)=O)[CH2:7][CH2:6][CH2:5][CH2:4][CH2:3]1.C1(P([N:32]=[N+]=[N-])(C2C=CC=CC=2)=O)C=CC=CC=1.CCO[C:38](C)=[O:39]>C1(C)C=CC=CC=1.CCCCCC>[C:12]1([CH:8]2[C:2]3([CH2:3][CH2:4][CH2:5][CH2:6][CH2:7]3)[O:1][C:38](=[O:39])[NH:32]2)[CH:13]=[CH:14][CH:15]=[CH:16][CH:17]=1To a 100 mL round bottom flask charged with 2-(1-hydroxycyclohexyl)-2-phenylacetic acid (6.5 g, 28.14 mmole, 1 eq.) in toluene (100 mL) were added TEA (2.5 eq) and diphenyl phosphoryl azide (2 eq). The resulting mixture was then stirred at 120° C. for 12 hours. Reaction progress was monitored by TLC (TLC eluent: 30% EtOAc in hexane). The reaction mixture was then cooled and toluene was removed under reduced pressure to afford the product. The product thus obtained was purified by column chromatography using silica gel and eluting with 10% EtOAc in hexane to afford 4-phenyl-1-oxa-3-azaspiro[4.5]decan-2-one (2 g, 31%). 1H NMR (400 MHz, DMSO-d6) δ: 8.04 (s, 1H), 7.26-7.41 (m, 5H), 4.54 (s, 1H), 1.93-1.97 (m, 1H), 1.48-1.78 (m, 4H), 1.12-1.33 (m, 5H). m/z (ESI) 232.1 (M+H)+.
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