Tetrahydrofuran → 7-Benzyl-4,7-diazaspiro[2.5]octane

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Reaction Steps

A borane-tetrahydrofuran complex (0.93 M tetrahydrofuran solution) (375 ml, 0.35 mol) was added to a tetrahydrofuran (200 ml) solution of the compound (20 g, 86.8 mmol) obtained in Step 2 above with ice cooling and then the resulting mixture was heated to reflux for 19 hours. Methanol (130 ml) was added to the reaction mixture with ice cooling, the resulting mixture was stirred for 60 minutes, and the solvent was concentrated under reduced pressure. Ethanol (450 ml), water (150 ml), and triethylamine (150 ml) were added to the resulting residue, the resulting mixture was heated to reflux for 2 hours, and then the solvent was concentrated under reduced pressure. The resulting residue was diluted with ethyl acetate, washed successively with saturated aqueous sodium bicarbonate solution and saturated brine, and then dried over anhydrous sodium sulfate. The solvent was evaporated under reduced pressure and the resulting residue was purified by silica gel column chromatography (chloroform:methanol=10:1) to give the title compound (10.4 g, 59%) as a colorless oil.

Provenance & Evidence