Boron trifluoride → Z-3-(3-Pyridinylmethyl)imino-10beta-piran-2-OL

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Reaction Steps

To a stirring solution of (+)-2-hydroxy-3-pinanone (10.00 g, 59.4 mmol) in benzene (500 mL) was added 3-pyridylmethylamine (6.66 mL, 65.4 mmol) in one portion. Boron trifluoride diethyletherate (0.7 mL, 5.9 mmol) was added in one portion and the reaction was refluxed under N2 for 5 h and then stirred at room temperature for an additional 16 h. The benzene was removed by rotary evaporation and the resulting residue was stirred in saturated NaHCO3 solution (100 mL) for 1 h. This was then extracted with chloroform (3×100 mL) and the combined extracts were dried (Na2SO4), filtered and concentrated by rotary evaporation. The resulting dark brown oil was purified by column chromatography, using a chloroform:methanol gradient (9:1 to 1:1, v/v) as eluent. The light yellow oil was then dissolved in hot ethyl acetate (50 mL) and placed in a −4° C. freezer for 16 h. After warming to room temperature, the resulting crystals were filtered, washed with cold ethyl acetate, and dried using a hi-vacuum pump to yield 8.59 g of white powder (52.4% yield).

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