A. L-Threitol 1,4-bismethanesulfonate . A dry, 1-L, round-bottomed flask equipped with a magnetic stirring bar, vacuum adapter, rubber septum, and a nitrogen line (Note 1) is charged with 2,3-O-isopropylidene-L-threitol (25.0 g, 0.154 mol) (Note 2), pumped under high vacuum for 10 min, and a nitrogen atmosphere is introduced. Methylene chloride (308 mL) (Note 3) and pyridine (37.4 mL, 0.462 mol) (Note 4) are added, and the stirred solution is cooled to 0°C with an ice-water bath. Methanesulfonyl chloride (29.8 mL, 0.385 mol) (Note 5) is added dropwise via a 50-mL glass syringe over a period of 10 min. After an additional 30 min, the ice-water bath is removed, and the stirred solution is allowed to warm to room temperature. After an additional 6 hr a precipitate forms ( pyridinium chloride ); 300 mL of an aqueous saturated solution of sodium bicarbonate (NaHCO₃) is added slowly, dissolving the precipitate. The solution is stirred for a further 30 min and then transferred to a 1-L separatory funnel. The layers are separated, and the aqueous layer is extracted with methylene chloride (3 × 100 mL). The organic layers are combined, dried with anhydrous sodium sulfate , and the drying agent is removed by filtration. The solvent is removed by rotary evaporation to give a tan solid that can be used as such or recrystallized (Note 6) from 1:1 chloroform-diethyl ether to give the product as a crystalline white solid, mp 77-78°C, 43 g (88% yield) (Note 7).

A 1-L, one-necked, round-bottomed flask equipped with a heating mantle, magnetic stirring bar, and a reflux condenser is charged with 2,3-O-isopropylidene-L-threitol 1,4-bismethanesulfonate (40 g, 0.126 mol), 95% ethanol (250 mL) (Note 8) and methanesulfonic acid (0.204 mL, 3.14 mmol) (Note 9), and brought to a gentle reflux. The solution is refluxed for 10 hr and then cooled to 0°C with an ice-water bath resulting in the formation of crystals. The crystals are collected by suction filtration, washed with cold ethanol (2 × 50 mL) and diethyl ether (2 × 50 mL), and dried in a vacuum desiccator at 60°C under full vacuum for 4 hr to give the product as white crystals, mp 101-102°C, 29.6 g, (84% yield) (Note 10).

B. (S,S)-1,2,3,4-Diepoxybutane. A 250-mL, two-necked, round-bottomed flask equipped with a magnetic stirring bar, nitrogen line, and a 125-mL pressure-equalizing addition funnel is charged with L-threitol 1,4-bismethanesulfonate (25.0 g, 0.0898 moles) and diethyl ether (180 mL). The mixture is stirred vigorously to form a suspension, and a solution of potassium hydroxide (11.6 g, 0.207 mol) (Note 11) in water (35 mL) is added dropwise via the addition funnel over a period of 15 min. The clear mixture is stirred for an additional 45 min at room temperature, and the ether layer is decanted. The aqueous layer is transferred to a 500-mL separatory funnel and extracted with methylene chloride (3 × 50 mL). The combined ether and methylene chloride extracts are dried with anhydrous sodium sulfate, the sodium sulfate is removed by filtration, and the solution is concentrated to approximately 50 mL total volume by rotary evaporation. The concentrate is fractionally distilled through a 13-cm Vigreux distillation column at atmospheric pressure to give the product as a clear oil, bp 138-140°C, 6.3 g (81%) (Note 12) and (Note 13).

C. (2S,3S)-Dihydroxy-1,4-diphenylbutane . A 500-mL, one-necked, round-bottomed flask is equipped with a vacuum adapter, septum, magnetic stirring bar and an argon line (Note 14). The flask is flame-dried under reduced pressure, an argon atmosphere is reintroduced, and copper iodide (CuI) (1.89 g, 9.9 mmol) (Note 15) is added. The flask with CuI is pumped under reduced pressure for 10 min, and the argon atmosphere is reintroduced. Then 30 mL of tetrahydrofuran (THF) (Note 16) is added to the flask, stirring is initiated, and the slurry is cooled to −30°C with a dry ice-bromobenzene bath. Phenylmagnesium bromide in THF (18.0 g, 0.099 mol, 99 mL of a 1 M solution in THF) (Note 17) is added via a 50-mL syringe over a period of 10 min, and the stirred slurry is aged a further 10 min. (S,S)-1,2,3,4-Diepoxybutane (2.84 g, 0.033 mol, 11 mL of a 3 M solution in THF) is added dropwise via syringe over a period of 10 min. After an additional 10 min at −30°C, the reaction mixture is warmed to 0°C with an ice-water bath. After an additional 2.5 hr at 0°C, the reaction is quenched by the slow addition of 200 mL of an aqueous saturated ammonium chloride solution, the ice-water bath is removed, and the quenched reaction is stirred for 15 min yielding a deep blue color. The reaction mixture is transferred to a 1-L separatory funnel, and the layers are separated. The aqueous layer is extracted with methylene chloride (4 × 50 mL), the combined organic layers are dried with magnesium sulfate the drying agent is removed by filtration, and solvent is removed by rotary evaporation to give 7.1 g of a light yellow solid. The solid is dissolved in 225 mL of toluene with heat (heating mantle) then and cooled to 0°C with an ice-water bath resulting in the formation of fine needles. The needles are collected via suction filtration and dried in a vacuum desiccator at 40°C under full vacuum for 6 hr to yield 6.0 g of a white solid. The filtrate is evaporated to dryness via rotary evaporation to yield 1.1 g of a yellow solid. The yellow solid is flash-chromatographed on 30 g of Merck 230-400 mesh silica gel with 1:1 hexanes-ethyl acetate to give 1.0 g of a white solid (Note 18). The combined recrystallized and chromatographed product yields a total of 7.0 g of diol (88%) (Note 19).