Reaktion #1256409

Reaktionsgleichung

(R)-4-benzyl-3-[5-(tert-butyl-diphenyl-silanyloxy)-pentanoyl]-oxazolidin-2-one

(−)-sparteine

trans-cinnamaldehyde

→

desired product

Ausbeute 83.2%

(4R)-4-Benzyl-3-{(2R,3R)-2-[3-(tert-butyl-diphenyl-silanyloxy)-propyl]-3-hydroxy-5-phenyl-pent-4-enoyl}-oxazolidin-2-one

Ausbeute 83.2%

Lösungsmittel

methylene chloride

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.WAITAfter 20 min
2. 2
   SonstigeThe reaction was quenched by the addition of 50% saturated ammonium chloride (50 mL)
3. 3
   workup.ADDITIONdiluted with water (100 mL)
4. 4
   Extraktionextracted with methylene chloride (3×30 mL)
5. 5
   Waschenwashed with brine
6. 6
   Trocknendried over sodium sulfate
7. 7
   Einengenconcentrated in vacuo to a colorless oil
8. 8
   SonstigeThe oil was purified by flash chromatography (SiO2, 15-30% ethyl acetate in hexanes)

Vorschrift

To a stirring solution of (R)-4-benzyl-3-[5-(tert-butyl-diphenyl-silanyloxy)-pentanoyl]-oxazolidin-2-one (1.64 g, 3.19 mmol) in dry methylene chloride (15.9 mL) in a flame dried round bottom flask under N2 at 0° C. was added titanium(IV) chloride (386 μL, 3.51 mmol). After 5 min, (−)-sparteine (1.83 mL, 7.97 mmol) was added. After 20 min, trans-cinnamaldehyde (442 μL, 3.51 mmol) was added dropwise to the purple suspension, and the resulting pale green-yellow solution was stirred for 1 h . The reaction was quenched by the addition of 50% saturated ammonium chloride (50 mL), diluted with water (100 mL), and then extracted with methylene chloride (3×30 mL). The organic layers were combined, washed with brine, dried over sodium sulfate, and concentrated in vacuo to a colorless oil. The oil was purified by flash chromatography (SiO2, 15-30% ethyl acetate in hexanes) to yield 1.72 g (83.1%) of the desired product as a white solid. MS (APCI), m+/z: (M+H)+=648.

Quelle