Cl[S:2]([C:5]1[CH:19]=[CH:18][C:8]([O:9][C:10]([CH3:17])([CH3:16])[C:11]([O:13][CH2:14][CH3:15])=[O:12])=[CH:7][CH:6]=1)(=O)=O.CCO.[Sn].Cl>C(Cl)Cl>[CH3:17][C:10]([O:9][C:8]1[CH:7]=[CH:6][C:5]([SH:2])=[CH:19][CH:18]=1)([CH3:16])[C:11]([O:13][CH2:14][CH3:15])=[O:12]To a 3-L three-neck round-bottom flask equipped with an overhead mechanical stirrer, addition funnel and a N2 inlet was added ethyl 2-[4-(chlorosulfonyl)phenoxy]-2-methylpropanoate (53 g, 0.173 moles, 1 eq) and absolute EtOH (500 ml). Tin powder (325 mesh, 123.06 g, 1.04 moles, 6 eq) was added as a solid. The overhead stirrer was adjusted so that the rotor is as close as possible to the bottom of the round-bottom flask and stirring speed was accelerated to a very high setting before adding the HCl to prevent the clumping of the tin metal. Hydrogen chloride (4N in dioxane, 300 ml) was added dropwise over the course of 1 hour. The reaction mixture was refluxed for 4 hours at which point the hot ethanolic solution was poured into a 2-L Erlenmeyer flask containing CH2Cl2 (1 L) and ice. After stirring for 10 minutes the biphasic mixture was filtered through Celite. After transferring to a separatory funnel the phases were separated and the aqueous fraction was washed with CH2Cl2 (2×100 ml). The combined organic fractions were dried over Na2SO4, filtered and concentrated in vacuo. A bright yellow oil with a white precipitate suspended resulted. This yellow mixture was dissolved in a minimum amount of CH2Cl2 and filtered once again through Celite to yield 30 g (75%) of a bright yellow oil.
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