Reaction #49995

Reaction equation

(3S,4S)-4-(1-hydroxymethylethenyl)-3-(1-(R)-benzyloxycarbonyloxyethyl)-1-di(p-anisyl)methyl-2-azetidinone

imidazole

t-butyldimethylchlorosilane

→

(3S,4S)-4-(1-t-butyldimethylsilyloxymethylethenyl)-3-(1-(R)-benzyloxycarbonyloxyethyl)-1-di(p-anisyl)methyl-2-azetidinone

Solvents

water

ethyl acetate

dimethylformamide

Conditions

Workup

1. 1
   ExtractionThe aqueous layer was extracted with ethyl acetate (150 ml)
2. 2
   WashThe combined extracts were washed successively with 5% hydrochloric acid solution (80 ml×2) and brine (80 ml)
3. 3
   Dryingdried over anhydrous sodium sulfate
4. 4
   FiltrationAfter filtration
5. 5
   Concentrationthe filtrate was concentrated in vacuo
6. 6
   Otherthe concentrate was crystallized from isopropanol

Procedure

A solution of (3S,4S)-4-(1-hydroxymethylethenyl)-3-(1-(R)-benzyloxycarbonyloxyethyl)-1-di(p-anisyl)methyl-2-azetidinone (20 g) and imidazole (5.6 g) in dry dimethylformamide (45 ml) was treated with t-butyldimethylchlorosilane (6.77 g) at room temperature for 2 hours. The reaction mixture was diluted with cold water (200 ml) and ethyl acetate (150 ml). The aqueous layer was extracted with ethyl acetate (150 ml). The combined extracts were washed successively with 5% hydrochloric acid solution (80 ml×2) and brine (80 ml), and dried over anhydrous sodium sulfate. After filtration, the filtrate was concentrated in vacuo, and the concentrate was crystallized from isopropanol to give crystals of (3S,4S)-4-(1-t-butyldimethylsilyloxymethylethenyl)-3-(1-(R)-benzyloxycarbonyloxyethyl)-1-di(p-anisyl)methyl-2-azetidinone. m.p., 90°-92° C.

Source