Methanol → 3-Cyclopentyloxy-4-methoxybenzenethiol

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Reaction Steps

A suspension of 3,3′-dicyclopentyloxy-4,4′-dimethoxyphenyldisulfide (15 g, Reference Example 3) and sodium borohydride (3.18 g) in anhydrous tetrahydrofuran (150 ml) at reflux was treated dropwise with anhydrous methanol (15 ml) over 1 hour. The cloudy yellow solution was stirred at reflux for 30 minutes then cooled to room temperature and stirring was continued for 18 hours. The reaction mixture was partitioned between hydrochloric acid (400 ml, 1N) and diethyl ether (400 ml). The aqueous layer was extracted three times with diethyl ether (200 ml). The combined organic phases were washed with hydrochloric acid (100 ml), then with water (100 ml) and then extracted three times with sodium hydroxide solution (200 ml, 0.2N) and once with water (200 ml). The combined aqueous extracts were acidified by addition of hydrochloric acid (1N) and then extracted five times with diethyl ether (200 ml). The combined ether extracts were washed with water (200 ml) then with brine (200 ml), then dried over magnesium sulphate and then evaporated to give the title compound (10.5 g) as a pale yellow oil. NMR (CDCl3): δ1.60 (m,2H), 1.80-2.00 (m,6H), 3.40 (s,1H), 3.80 (s,3H), 4.73 (m,1 H), 6.74 (d,1H), 6.88 (dd,2H). Mass spectrum (FAB): m/z 224 (M)+.

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