Ethyl Acetate → [7-(Benzyloxy)-8-(2-hydroxyethyl)-2,3-dihydro-1,4-benzodioxin-2-yl]methyl 4-methylbenzenesulfonate

Participants

Reaction Steps

To a solution of 3.9 g (8.4 mmole) of [(2R)-8-allyl-7-(benzyloxy)-2,3-dihydro-1,4-bezodioxin-2-yl]methyl 4-methylbenzenesulfonate in 300 mL of tetrahydrofuran was added 1.8 mL (0.30 mmole) of 4% aqueous osmium tetroxide. The solution was stirred at room temperature under nitrogen for 30 minutes, then a solution of 9.0 g (40 mmole) of sodium periodate in 75 mL of water was added dropwise over a 30 10 minute period. The mixture was allowed to stir at room temperature under nitrogen for 15 hours. Ethyl acetate (400 mL) was then added and the solution was washed twice with 300 mL portions of water and with saturated brine, dried over sodium sulfate, filtered and concentrated in vacuum to 2.8 g of a colorless oil. The oil was redissolved in 100 mL of methylene chloride, 3.0 g (12 mmole) of tetra-n-butylammonium borohydride added and the mixture stirred at room temperature for 15 hours. The excess reducing agent was then destroyed by the cautious addition of 200 mL of 1 N aqueous HCl, the organic phase removed in a separatory funnel, and the aqueous back-extracted with 100 mL of methylene chloride. The combined organic phases were washed with 250 mL of saturated brine, dried over sodium sulfate, filtered and concentrated in vacuum. The residue was column chromatographed on silica gel with first methylene chloride, then 2% methanol in methylene chloride, to give 2.3 g of the (R)-enantiomer of the title compound as a colorless oil. 1H-NMR (CDCl3): doublet 7.8 δ (2H); multiplet 7.4 δ (5H); doublet 7.37 δ (2H); doublet 6.65 δ (1H); doublet 6.45 δ (1H); singlet 5.0 δ (2H); multiplet 4.43 δ (1H); multiplet 4.2 δ (3H); doublet of doublets 4.0 δ (1H); triplet 3.73 δ (2H), triplet 2.9 δ (2H); singlet 2.43 δ (3H); broad singlet 1.65 δ (1H).

Provenance & Evidence