Sodium borohydride → HCID 58423839, compound

Participants

Reaction Steps

In a 25 mL round bottom flask was placed 6-bromospiro[chroman-2,1′-cyclohexane]-4,4′-dione (240 mg, 0.779 mmol) and it was dissolved in THF (7.8 mL). To this solution was added NaBH4 (30 mg, 0.789 mmol) and the reaction was allowed to stir at room temperature for 5 minutes. At that time, TLC indicated total consumption of the diketone. The reaction was diluted with water (10 mL) and ethyl acetate (10 mL) and it was allowed to stir for 15 minutes. The phases were separated and the aqueous phase was back-extracted with ethyl acetate twice (5 mL/each). The combined organic phases were washed with brine, dried over Na2SO4, filtered and concentrated under reduce pressure. The crude material was purified by flash chromatography (ISCO, 40 g SiO2 cartridge, ethyl acetate/hexanes as the eluents). A 3:1 mixture of separable isomers formed. The less-polar product (judge by TLC) was cleanly separated by flash chromatography (ISCO, 40 g SiO2 cartridge, ethyl acetate/hexanes as the eluents) and use for further development. The corresponding fractions for less-polar product were combined and concentrated under reduce pressure yielding one of the isomers of 6-bromo-4′-hydroxyspiro[chroman-2,1′-cyclohexan]-4-one (58 mg, 0.187 mmol, 24% yield).

Provenance & Evidence