2-Benzhydryl-5-oxa-2,8-diazaspiro[3.5]nonan-7-one → 2-(Diphenylmethyl)-5-oxa-2,8-diazaspiro[3.5]nonane

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Reaction Steps

Borane-methyl sulfide complex in THF (13.38 mL) was added in one portion to 2-benzhydryl-5-oxa-2,8-diazaspiro[3.5]nonan-7-one (2.5 g) (WO2009098448, example 33, step e) in THF (50 mL) at room temperature under argon. The resulting solution was stirred at reflux for 90 minutes. The reaction was cooled to room temperature then the reaction mixture was quenched with methanol (50.0 mL). N,N′-Dimethylethylenediamine (5.18 mL) was added and the reaction mixture allowed to stir at room temperature for 1 week. The reaction mixture was evaporated to dryness and re-dissolved in ethyl acetate (250 mL), and washed with water (250 mL). The organic layer was dried over MgSO4, filtered and evaporated to afford crude product. The crude product was dissolved in iso-hexane (10 mL) and was purified by flash silica chromatography, eluting with 10% methanolic ammonia in DCM. Pure fractions were evaporated to dryness to afford 2-benzhydryl-5-oxa-2,8-diazaspiro[3.5]nonane. Yield 1.647 g.

Provenance & Evidence