Reaction #160822

Reaction equation

HCl

diisobutylaluminum hydride

ethyl 3-(6-oxocyclohex-1-en-1-yl)propanoate

diisobutylaluminum hydride

→

title compound

3,4,6,7,8,8a-hexahydro-2H-chromene

Solvents

Et2O

THF

Conditions

Workup

1. 1
   Temperaturewarmed to RT
2. 2
   workup.STIRRINGstirred for one more hour
3. 3
   workup.ADDITIONwas added the reaction
4. 4
   workup.STIRRINGstirred at RT for two hours
5. 5
   TemperatureThe reaction was then cooled to −78° C.
6. 6
   workup.ADDITIONAfter the addition
7. 7
   Otherto return to RT
8. 8
   workup.STIRRINGwas stirred overnight
9. 9
   Washthen washed 2× with water
10. 10
    DryingThe organic layer was dried over Na2SO4
11. 11
    Filtrationthen filtered
12. 12
    Concentrationconcentrated
13. 13
    Otherpurified on silica gel

Procedure

A solution of 48 mL diisobutylaluminum hydride (1.0 M in cyclohexane) was cooled to −78° C. and a solution of 2.335 g ethyl 3-(6-oxocyclohex-1-en-1-yl)propanoate in 48 mL THF was added. The reaction was warmed to 0° C. and stirred for one hour, then warmed to RT and stirred for one more hour. The reaction was not complete at this point, so 10 mL additional diisobutylaluminum hydride solution was added the reaction was and stirred at RT for two hours. The reaction was then cooled to −78° C. and then 25 mL 6 M HCl was added dropwise. After the addition was complete, the reaction was allowed to return to RT and was stirred overnight. The reaction was diluted with 200 mL Et2O then washed 2× with water, then with brine. The organic layer was dried over Na2SO4 then filtered, concentrated, and purified on silica gel to provide the title compound.

Source