2,6-Lutidine → (4R)-4-benzyl-3-[(2R,3R)-2-styryl-tetrahydro-pyran-3-carbonyl]-oxazolidin-2-one

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Reaction Steps

To a stirring solution of (4R)-4-benzyl-3-[(2R,3R)-3-hydroxy-2-(3-hydroxy-propyl)-5-phenyl-pent-4-enoyl]-oxazolidin-2-one (3.88 g, 9.49 mmol) in anhydrous methylene chloride (100 mL) in a flame-dried round bottom flask under N2 at −78° C. was added 2,6-lutidine (2.76 mL, 23.7 mmol). Trifluoromethanesulfonic anhydride (1.68 mL, 9.96 mmol) was then added dropwise; after 5 min, the reaction was quenched with saturated aqueous sodium bicarbonate (50 mL), the layers were separated, and the aqueous layer was washed with methylene chloride (2×50 mL). The combined organic layers were dried over sodium sulfate, concentrated in vacuo, and purified by flash chromatography (SiO2, 20-30% ethyl acetate in hexanes) to yield a pale yellow oil. The resulting oil was diluted with ethyl acetate (50 mL), the organic layer was washed once with 1N aqueous hydrogen chloride (50 mL) to remove residual 2,6-lutidine, and the ethyl acetate was concentrated in vacuo to yield the desired tetrahydropyran (2.35 g, 63.3%) as a pale yellow oil. MS (APCI), m+/z: (M+H)+=392.4.

Provenance & Evidence