[CH3:1][C:2]1[CH:3]=[C:4]([S:8][CH2:9][CH2:10][C:11]([OH:13])=O)[CH:5]=[CH:6][CH:7]=1.FC(F)(F)C(OC(=O)C(F)(F)F)=O.C([O-])([O-])=O.[Na+].[Na+].CCOCC.CCCCCC>FC(F)(F)C(O)=O>[CH3:1][C:2]1[CH:3]=[C:4]2[C:5]([C:11](=[O:13])[CH2:10][CH2:9][S:8]2)=[CH:6][CH:7]=13-(3-Methylphenylthio)propanoic acid from Step 1 (10.12 g, 52 mmol) was dissolved in trifluoroacetic acid (20 mL), treated with trifluoroacetic anhydride (10 mL) and stirred at room temperature for 1.9 hours. The reaction was poured into 10% Na2CO3 (100 mL), extracted with ether, washed with brine, dried over MgSO4, and concentrated in vacuo to give an orange oil which was passed through a column of silica gel eluting with 8% ether/hexane to give 7-methylthiochroman-4-one (2.97 g, 32%) as a yellow oil: 1H NMR (CDCl3) 300 MHz 7.97 (d, J=8.1 Hz, 1H) 7.06 (s, 1H) 6.97 (d, J=7.7 Hz, 1H) 3.17 (m, 2H) 2.95 (m, 2H) 2.31 (s, 3H). Mass spectrum: M+H=179.
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