[C:1]1(=[O:14])[C:10]2[C:5](=CC(C(O)=O)=C[CH:9]=2)[CH2:4][CH2:3][CH2:2]1.O[N:16]1[C:20](=[O:21])[CH2:19][CH2:18][C:17]1=O.C1(N=C=NC2CCCCC2)CCCCC1.[Cl-].[NH4+].C(N(CC)CC)C>C(Cl)Cl>[CH2:2]1[C:3]2[C:17](=[CH:18][C:19]([C:20]([NH2:16])=[O:21])=[CH:5][CH:4]=2)[CH2:9][CH2:10][C:1]1=[O:14]Tetralone-6-carboxylic acid, ethylene ketal (395 mg, 2.07 mmol) was co-dissolved in CH2Cl2 (50 mL) with N-hydroxysuccinimide (260 mg, 2.76 mmol) at 0° C. and treated with a slight excess of 1,3-dicyclohexylcarbodiimide (502 mg, 2.50 mmol). The mixture was allowed to warm to ambient temperature over 30 minutes, during which time a fine white precipitate formed. Ammonium chloride (333 mg, 6.23 mmol) and triethylamine (1.58 mL, 12.5 mmol, d=0.797) were added. The solution was stirred at ambient temperature for 16 hours. The suspended urea and salts were filtered away and the solution concentrated in vacuo to a colorless oil. The oil was applied to a silica flash chromatography column and eluted with 50-100% EtOAc in hexanes to yield 250 mg (64%) of 2-tetralone-6-carboxamide, ethylene ketal as a white solid, clean by NMR, TLC.
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