Reaction #1429

Reaction equation

cesium carbonate

(S)-2-phthalimido-6-hydroxyhexanoic acid

benzyl bromide

→

title product

(S)-2-Phthalimido-6-hydroxyhexanoic acid, phenylmethyl ester

Solvents

dimethylformamide

Conditions

Workup

1. 1
   Otherthe mixture was partitioned between ethyl acetate and water
2. 2
   ExtractionThe organic extract
3. 3
   Washwas washed with water (twice) and brine
4. 4
   Dryingdried (sodium sulfate)
5. 5
   Filtrationfiltered
6. 6
   Otherto give an oil
7. 7
   Otherchromatographed (Merck silica gel, 6/4-ethyl acetate/hexane)
8. 8
   Otherto give essentially pure product as a solid
9. 9
   OtherRecrystallization from ethyl acetate/hexane
10. 10
    Othergave 7.173 g

Procedure

A slurry of cesium carbonate (3.819 g, 11.7 mmol.) and (S)-2-phthalimido-6-hydroxyhexanoic acid (6.00 g, 21.6 mmol.) in dimethylformamide (60 ml.) was treated with benzyl bromide (3.30 ml., 4.75 g., 27.7 mmol.). After stirring at room temperature for 2 hours, the mixture was partitioned between ethyl acetate and water. The organic extract was washed with water (twice) and brine, then dried (sodium sulfate), filtered and stripped to give an oil. The oil was flash chromatographed (Merck silica gel, 6/4-ethyl acetate/hexane) to give essentially pure product as a solid. Recrystallization from ethyl acetate/hexane gave 7.173 g. (1st crop) and 394 mg. (2nd crop) for a total of 7.567 g. of pure title product; m.p. 106°-108.5° C.; [α]D =-27.5° (c=1.5, methanol). TLC (75/25 ethyl acetate/hexanes) Rf =0.43.

Source