Lawesson's reagent → HCID 11438051, compound

Participants

Reaction Steps

Estrone methyl ether (2, 17.64 g, 62.2 mmol) was dissolved in 500 mL of dry tetrahydrofuran (THF) and a first portion of Lawesson's reagent (13 g, 32 mmol) was added. The reaction mixture containing suspended solid was heated to reflux for 18 h when all solids dissolved and the solution became salmon red. A second portion of Lawesson's reagent (13 g, 32 mmol) was added and heating continued at reflux temperature for another 18 h. Similarly, a third portion of Lawesson's reagent (13 g, 32 mmol) was added; and after being heated for 18 h, the reaction mixture was cooled and the THF evaporated to give a thick slurry. The slurry was dissolved in a minimum amount of CH2Cl2 and passed through a pad of silica gel to remove a polar by-product of Lawesson's reagent. The eluent was concentrated to afford a bright orange solid which was further purified by column chromatography on silica gel with EtOAc-Hexanes (1:3) as eluent to afford a bright orange solid product (10.5 g, 35 mmol) in 56% yield as the first fraction and then starting material (4 g, 14.0 mmol) in 23% recovery. Crude thione 3 can be further purified by crystallizing from boiling EtOAc, although after column purification it is pure enough for subsequent reactions. 1H NMR (250 MHz, CDCl3) δ 0.94 (s, 3, C-S 8 CH3), 3.78 (s, 3, --OCH3), 6.64-6.75 (m, 2, ArH), 7.22 (d, J=10 Hz, 1 ArH); 13C NMR (250 MHz, CDCl3) δ 273.3 (C=S).

Provenance & Evidence