To a solution of 4a-methyl-6-(phenylsulfanyl)-1,2,3,4,4a,9a-hexahydro[1]benzofuro[2,3-c]pyridine-2-carboxylic acid tert-butyl ester (0.327 g, 0.82 mmol) in methanol (10 mL, 0.2 mol) was added water (0.5 mL, 0.03 mol) and Oxone® (2.0 g, 0.0032 mol). The reaction was stirred overnight at room temperature. The reaction mixture was filtered and the filtrate concentrated. The residue was dissolved in DCM and washed with brine, dried, filtered and concentrated. The crude product was purified on a 12 g silica gel column eluting with hexanes to 2:1 hexanes:ethyl acetate and then stirred in 4 M HCl in dioxane (5 mL, 0.04 mol) for 30 min. The product was precipitated by addition of DCM and ether. The solid was filtered, washed with ether and dried under house vacuum to afford the title compound. mp 236-238° C. dec.; MS m/z 330 [M+H]+. 1H-NMR (400 MHz, DMSO): δ 1.45 (s, 3H), 1.75 (m, 1H), 1.90 (m, 1H), 2.82 (m, 1H), 3.03 (m, 1H), 3.35-3.56 (m, 2H), 4.63 (s, 1H), 7.08 (d, J=8.9 Hz, 1H), 7.58-7.70 (m, 3H), 7.81 (d, J=8.85 Hz, 1H), 7.91-7.96 (m, 3H), 8.91 (bs, 1H), 9.91 (bs, 1H).
