909034-76-0

180160-97-8

The general procedure for the synthesis of spiro[isobenzodihydropyran-1,4'-piperidine]-1'-carboxylic acid tert-butyl ester from spiro[isobenzodihydropyran-1,4'-piperidine] is as follows: Step 1: Deprotection reaction Trifluoroacetic acid (15 mL) was added to a solution of tert-butyl spiro[isobenzodihydropyran-1,4'-piperidine]-1'-carboxylate (3.3 g, 10.87 mmol) in dichloromethane (15 mL), and the reaction was stirred for 2 h at room temperature. Step 2: Post-treatment The reaction mixture was concentrated under reduced pressure and the residue was redissolved in dichloromethane (15 mL). Alkalization was carried out by adjusting the pH to 8 with aqueous sodium carbonate. The organic and aqueous phases were separated and the organic phase was washed sequentially with water, sodium bicarbonate solution and saturated saline. The organic phase was dried over anhydrous sodium sulfate and the solvent was evaporated under reduced pressure. Step 3: Purification The obtained residue was ground with ether to obtain white solid spiro[isobenzodihydropyran-1,4'-piperidine] (1.35 g, 64% yield). Characterization data: 1H NMR (DMSO-d6, 400 MHz) δ: 1.88 (m, 2H), 2.09 (m, 2H), 2.77 (t, 2H), 3.02 (m, 2H), 3.15 (m, 2H), 3.90 (t, 2H), 7.10-7.28 (m, 4H). LRMS: m/z APCI+ 204 [MH]+.