Ammonia → US8975415, RP1a

Participants

Reaction Conditions

Reaction Steps

To an ice chilled solution of 6-bromo-4-methylene-4′,5′-dihydro-3′H,4H-spiro[chromene-3,2′-furan] (497 mg, 1.77 mmol) in EtOAc (2.5 ml) and MeCN (2.5 ml) was added silver cyanate (397 mg, 2.65 mmol) in an ice bath under an argon atmosphere. To the mixture was added iodine (673 mg, 2.65 mmol). After stirring for 30 minutes in the ice bath and 30 minutes at ambient temperature, the mixture was filtered through celite. The filtrate was washed with saturated aqueous Na2S2O3. The organic layer was washed with brine, dried over Na2SO4, filtered, and the filtrate was evaporated to give an oil. The oil was dissolved in THF (5 mL) and a 2M EtOH solution of NH3 (4.5 ml, 9.0 mmol) was added under ice bath cooling. The mixture was stirred overnight under ice bath cooling and for 1 hour at 70° C. After concentration in vacuo, the residue was diluted with saturated aqueous NaHCO3 and extracted with CHCl3. The organic layer was washed with brine, dried over Na2SO4, filtered, and the filtrate was evaporated off. The residue was purified by silica gel chromatography(CHCl3/EtOH=100:0-90:10) to give less polar diastereomer of 6′-bromo-4,5-dihydro-3H-dispiro[furan-2,3′-chromene-4′,4″-[1,3]oxazol]-2″-amine (178 mg) and polar diastereomer of 6′-bromo-4,5-dihydro-3H-dispiro[furan-2,3′-chromene-4′,4″-[1,3]oxazol]-2″-amine (367 mg).

Provenance & Evidence