Triphenylphosphine → 6-bromo-2,2-dimethyl-4H-spiro[chromene-3,3'-oxetan]-4-one

Beteiligte Stoffe

Reaktionsschritte

To a mixture of 6-bromo-3,3-bis(hydroxymethyl)-2,2-dimethyl-2,3-dihydro-4H-chromen-4-one (6.76 g, 21.4 mmol), zinc bis(dimethyldithiocarbamate) (26.2 g, 85.8 mmol) and triphenylphosphine (8.44 g, 32.2 mmol) in THF (0.20 L) was added diisopropyl azodicarboxylate (1.9 M solution in toluene, 16.9 mL, 32.2 mmol) in an ice-water bath. The mixture was stirred overnight at ambient temperature. The mixture was diluted with toluene (0.20 L), and the mixture was filtered off. The filtrate was washed with 1 M aqueous NaOH (three times), water and brine, dried over MgSO4 and filtered. The filtrate was evaporated to give a crude product. The crude product was purified with column chromatography on silica gel (Hexane-EtOAc, a linear gradient of EtOAc from 0 to 20%) to afford 6-bromo-2,2-dimethyl-4H-spiro[chromene-3,3′-oxetan]-4-one (2.22 g).

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