Reaction #93186

Reaction equation

6-cyano-3,4-dihydro-2,2-dimethyl-trans-3-bromo-4-hydroxy-2H-benzo[b]pyran

sodium hydride

2-Pyrrolidone

sodium hydride

6-cyano-3,4-dihydro-2,2-dimethyl-3,4-epoxy-2H-benzo[b]pyran

→

title compound

Yield 60.0%

6-Cyano-3,4-dihydro-2,2-dimethyl-trans-4-(2-oxo-1-pyrrolidinyl)-2H-benzo[b]pyran-3-ol

Yield 60.0%

Solvents

Water

dimethylsulphoxide

Conditions

Workup

1. 1
   Otherresulted
2. 2
   Othercrystallisation of the product after which it
3. 3
   Temperaturewas cooled in ice
4. 4
   Filtrationfiltered under suction
5. 5
   OtherCrystallisation from ethanol (20 ml)

Procedure

A solution of 6-cyano-3,4-dihydro-2,2-dimethyl-trans-3-bromo-4-hydroxy-2H-benzo[b]pyran (4 g, 14.2 mM) in dimethylsulphoxide (20 ml) was stirred and sodium hydride (60% dispersion in oil, 0.6 g, 15 mM) added. The suspension was stirred for 1 hour when a solution of 6-cyano-3,4-dihydro-2,2-dimethyl-3,4-epoxy-2H-benzo[b]pyran resulted. 2-Pyrrolidone (1.8 g, 21 mM) and further sodium hydride (0.8 g, 21 mM) were introduced and the mixture stirred at room temperature for an additional 16 hours. Water (40 ml) was slowly added to the mixture to induce crystallisation of the product after which it was cooled in ice and filtered under suction. Crystallisation from ethanol (20 ml) gave the title compound as a cream coloured solid in 60% yield. Recrystallisation from ethyl acetate afforded the pure product as needles, m.p. 226.5°-227.5° having an nmr spectrum and t.l.c. characteristics identical to those of the compound of Description 6.

Source