C([Li])CCC.C(NC(C)C)(C)C.[CH3:13][CH:14]1[CH2:19][CH2:18][O:17][C:15]1=[O:16].[CH3:20][S:21]SC>O1CCCC1>[CH3:13][C:14]1([S:21][CH3:20])[CH2:19][CH2:18][O:17][C:15]1=[O:16]Under an argon atmosphere, n-butyllithium (1.7 M in hexane, 1800 ml, 3.06 mole) was added slowly to a stirred solution of diisopropylamine (309.4 g, 3.06 mole) in tetrahydrofuran (1800 ml) at -78° C. Upon completion of addition, the reaction mixture was allowed to stir for 30 minutes at which time alpha-methyl-gamma-butyrolactone (278.0 g, 2.78 mole) was added dropwise, also at -78° C. The reaction mixture was stirred 30 minutes then dimethyl disulfide (392.8 g, 4.17 mole) was added dropwise. After stirring for 30 minutes at -78° C., the reaction mixture was warmed to ambient temperature during a one hour period. The reaction mixture was quenched with 5% aqueous hydrochloric acid (1500 ml) and then diluted with ethyl acetate (2000 ml). The layers were separated, and the organic layer was washed with aqueous 10% hydrochloric acid (1×200 ml) and then saturated aqueous sodium bicarbonate (1×100 ml). The organic layer was dried and concentrated under reduced pressure. The residue was distilled to yield 234.6 g of alpha-methyl-alpha-methylthio-gamma-butyrolactone as a colorless oil, b.p. 104°-105° C./8 mm Hg. The NMR spectrum was consistent with the proposed structure.
Loading…
