Benzene → 6,7-Dichloro-2,3-dihydro-1H-inden-1-one

Thionyl chloride (5.73 mL, ˜79 mmol) and 2,3-dichloro-benzoic acid (commercially available from Aldrich) (10.0 g, 52.4 mmol) in benzene was heated to reflux until no more gas evolution was observed. After cooling to rt the mixture was concentrated. The concentrate was diluted with dichloroethane and added to AlCl3 (7.0 g, ˜53 mmol) in dichloroethane at 10-20° C. Ethylene was bubbled through the mixture for 4 h. The mixture was stirred overnight and quenched with 4 N HCl. The resulting layers were separated and the aqueous layer was extracted with Et2O (3×250 mL). The combined organic extracts were washed with H2O (3×150 mL), saturated NaHCO3 (3×150 mL), brine (1×50 mL), dried over MgSO4 and concentrated. The concentrate was added to a slurry of AlCl3 (9.0 g) and NaCl (2.4 g) at 130° C. The resulting mixture was stirred at 180° C. for 2 hours after which it was cooled to room temperature and quenched with ice followed by concentrated HCl. The mixture was extracted with CH2Cl2 (3×500 mL) and the combined organic extracts were concentrated and purified by column chromatography using 20% EtOAc:hexane eluant to give 6.8 g (80%) of 6,7-dichloro-1-indanone. Use of 6,7-dichloro-indan-1-one in Method NINETEEN produced 4-(4,5-dichloro-indan-2-yl)-1,3-dihydro-imidazole-2-thione (Compound 153).