Reaction #1542638

Reaction equation

water

Sodium hydride

diethylcarbonate

1,4-cyclohexanedione mono-ethylene ketal

→

8-Oxo-1,4-dioxa-spiro[4.5]decane-7-carboxylic acid ethyl ester

Solvents

THF

acetic acid

hexane

THF

Conditions

Workup

1. 1
   TemperatureThe suspension was heated
2. 2
   Temperatureto reflux
3. 3
   workup.ADDITIONAfter the addition
4. 4
   Temperaturewas heated
5. 5
   Temperatureto reflux for an additional 4 hours
6. 6
   workup.ADDITIONpoured
7. 7
   ExtractionThe resulting mixture was extracted with hexane (2 L total)
8. 8
   Washthe extracts washed with water and brine
9. 9
   ExtractionThe hexane extract
10. 10
    Dryingwas dried over Na2SO4
11. 11
    Filtrationfiltered
12. 12
    Concentrationconcentrated

Procedure

Sodium hydride (60% dispersion; 45 g, 1.17 mol) was washed with 500 ml of hexane (2×), suspended in 750 mL of THF and treated with diethylcarbonate (112.5 g, 0.94 mol). The suspension was heated to reflux and treated drop-wise with a solution of 1,4-cyclohexanedione mono-ethylene ketal (60.0 g , 0.384 mol) in THF (250 mL). After the addition was complete the suspension was heated to reflux for an additional 4 hours. The mixture was cooled in an ice bath to 0° C. and then poured, while vigorously stirring, into a mixture of ice (1 L), water (100 mL) and acetic acid (100 mL). The resulting mixture was extracted with hexane (2 L total) and the extracts washed with water and brine. The hexane extract was dried over Na2SO4, filtered and concentrated to give 8-Oxo-1,4-dioxa-spiro[4.5]decane-7-carboxylic acid ethyl ester as a pale yellow oil. This was used without further purification.

Source