反应详情

温度

-70 °C

2 ml of a solution of 1.6M of tert.-butyllithium in pentane were added dropwise at -70° C. under an inert atmosphere to a stirred mixture of 950 mg of the tetrafluoroborate of isopropyldiphenylsulfonium in 15 ml of tetrahydrofuran and the mixture was stirred at -70° C. for 30 minutes to obtain a solution of diphenylisopropylidene sulfurane. The said solution at -70° C. was added slowly with stirring under an inert atmosphere to a mixture of 350 mg of 5(RS)methoxy-2,5-dihydrofuran-2-one [prepared by method of Schroeter et al, Liebigs Ann. Chem., Vol. 697 (1966), p. 42] and 15 ml of tetrahydrofuran cooled to -90° C. and the mixture was allowed to stand at -78° C. for one hour and then at -50° C. for another hour. The mixture was poured into an aqueous monosodium phosphate solution and the mixture was extracted with methylene chloride. The organic phase was evaporated to dryness under reduced pressure and the residue was chromatographed over silica gel. Elution with a 1-1 ether-petroleum ether mixture yielded 480 mg of diphenyl sulfide, 260 mg of (1RS,5SR)6,6-dimethyl-4(RS)-methoxy-3-oxabicyclo[3,1,0]hexan-2-one and 100 mg of unreacted lactone.