Reaction #7964

Reaction equation

allyl bromide

9a-butyl-7-methoxymethoxy-4-methyl-1,2,9,9a-tetrahydro-3H-fluoren-3-one

LDA

HCl

dry ice acetone

→

(2SR,9aSR)-2-allyl-9a-butyl-7-methoxymethoxy-4-methyl-1,2,9,9a-tetrahydro-3H-fluoren-3-one

Solvents

EtOAc

THF

THF

Conditions

Workup

1. 1
   workup.STIRRINGThe resulting solution was stirred at 0° C. for 30 minutes
2. 2
   workup.STIRRINGthen stirred at room temperature overnight
3. 3
   ExtractionThe aqueous phase was extracted with EtOAc (20 mL)
4. 4
   Washthe combined organics were washed with 5% NaHCO3 and brine
5. 5
   Dryingdried over MgSO4
6. 6
   Filtrationfiltered
7. 7
   Concentrationconcentrated under vacuum to a yellow oil
8. 8
   OtherThe crude product was purified by preparative layer chromatography on three 0.1×20×20 silica gel GF plates
9. 9
   WashThe UV visible band at Rf 0.44-0.56 was eluted with EtOAc
10. 10
    Otherthe eluant evaporated under vacuum

Procedure

A solution of 9a-butyl-7-methoxymethoxy-4-methyl-1,2,9,9a-tetrahydro-3H-fluoren-3-one (230 mg, 0.73 mmol) in anhydrous THF (3.8 mL) was cooled in an ice bath, stirred under a nitrogen atmosphere, and treated with freshly prepared 0.4M LDA in THF (2.2 mL, 0.88 mmol). The resulting solution was stirred at 0° C. for 30 minutes, then cooled to −78° C. (dry ice-acetone bath) and treated with allyl bromide (0.316 mL, 3.65 mmol). The reaction mixture was allowed to gradually warm to room temperature then stirred at room temperature overnight. The mixture was diluted with EtOAc (60 mL) and shaken with 1N HCl (35 mL). The aqueous phase was extracted with EtOAc (20 mL) and the combined organics were washed with 5% NaHCO3 and brine, dried over MgSO4, filtered, and concentrated under vacuum to a yellow oil. The crude product was purified by preparative layer chromatography on three 0.1×20×20 silica gel GF plates using 4:1 hexanes-EtOAc as developing solvent. The UV visible band at Rf 0.44-0.56 was eluted with EtOAc and the eluant evaporated under vacuum to afford (2SR,9aSR)-2-allyl-9a-butyl-7-methoxymethoxy-4-methyl-1,2,9,9a-tetrahydro-3H-fluoren-3-one (193 mg) as an oil.

Source