Hydrochloric Acid → 8-Benzyl-8-azabicyclo(3.2.1)octan-3-one

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Reaction Steps

A mixture of 2,5-dimethoxy tetrahydrofuran (20.5 g, 155.1 mmol), water (42.5 mL) and concentrated HCl (30 mL) was stirred at room temperature for about 30 minutes. To this stirring mixture was sequentially added water (62.5 mL), a premixed solution of benzylamine (17.9 mL, 162.9 mmol), water (87.5 mL) and concentrated HCl (23 mL), a premixed solution of 1,3-acetonedicarboxylic acid (25 g) and water (100 mL), and a solution of Na2HPO4 (16.5 g) in water (50 mL). The resulting mixture was adjusted to pH 4 to 5 with 40% aqueous NaOH and stirred overnight at room temperature. The mixture was acidified to pH 3 with concentrated HCl and heated to 85° C. for 3 hours. After cooling to room temperature, the mixture was basified with 20% aqueous NaOH, saturated with solid sodium chloride and extracted with dichloromethane. The organic layer was washed with brine, dried over sodium sulfate, filtered and concentrated to give a dark oil which was purified by flash column chromatography. The product was eluted with 20% ethyl acetate/hexanes. Desired fractions were combined and concentrated to give the title intermediate as a yellowish oil (16.17 g).

Provenance & Evidence