Lithium Hexamethyldisilazide → tert-butyl [(4'R)-6'-amino-2',2'-dimethyldispiro[cyclopropane-1,3'-chromene-4',4''-[1,3]oxazol]-2''-yl]carbamate

Participants

Reaction Conditions

Reaction Steps

To a mixture of di-tert-butyl[(4′R)-6′-bromo-2′,2′-dimethyldispiro[cyclopropane-1,3′-chromene-4′,4″-[1,3]oxazol]-2″-yl]imidodicarbonate (1.98 g, 3.68 mmol), bis(dibenzylideneacetone)palladium(0) (212 mg, 0.369 mmol), and tri-tert-butylphosphonium tetrafluoroborate (108 mg, 0.371 mmol) was added lithium bis(trimethylsilyl)amide (1M solution in toluene, 18 ml, 18 mmol) at room temperature under argon atmosphere. The mixture was stirred at 60° C. for 2 hours and then quenched with saturated aqueous ammonium chloride. The mixture was extracted with chloroform. The organic layer was dried over anhydrous magnesium sulfate, and concentrated in vacuo. The residue was purified by silica gel column chromatography (hexane/ethyl acetate=100:0-50:50-0:100) to afford tert-butyl[(4′R)-6′-amino-2′,2′-dimethyldispiro[cyclopropane-1,3′-chromene-4′,4″-[1,3]oxazol]-2″-yl]carbamate (1.37 g).

Provenance & Evidence