Réaction #50179

Équation de réaction

4-methoxy-4-(3-hydroxyprop-1-ynyl)tetrahydropyran

RED-AL

→

4-methoxy-4-(3-hydroxy -trans-prop-1-enyl)tetrahydropyran

Rendement 48.0%

Solvants

THF

Conditions de réaction

Traitement

1. 1
   AutreThe cooling bath was removed
2. 2
   Autrequenched by addition of crushed ice and saturated aqueous NH4Cl
3. 3
   ExtractionThe resulting two-phase mixture was extracted with ethyl acetate (4×90 mL)
4. 4
   SéchageThe combined organic layers were dried over MgSO4
5. 5
   Filtrationfiltered
6. 6
   Concentrationconcentrated in vacuo
7. 7
   AutrePurification by chromatography on silica gel (100 g, 10% ethyl acetate: hexanes)

Mode opératoire

A solution of 4-methoxy-4-(3-hydroxyprop-1-ynyl)tetrahydropyran (10.8 g, 44.9 mmol), prepared as in step 3, in dry THF (100 mL) was cooled to -75° C., and RED-AL (sodium bis(2-methoxyethoxy)aluminum hydride, Aldrich Chemical Co., 20 mL of 3.4M solution in toluene, 68 mmol) was added under a dry argon atmosphere. The cooling bath was removed and the reaction was warmed to 0° C. and quenched by addition of crushed ice and saturated aqueous NH4Cl. The resulting two-phase mixture was extracted with ethyl acetate (4×90 mL). The combined organic layers were dried over MgSO4, filtered, and concentrated in vacuo. Purification by chromatography on silica gel (100 g, 10% ethyl acetate: hexanes) provided 4-methoxy-4-(3-hydroxy -trans-prop-1-enyl)tetrahydropyran(3.71 g, 34 %) as a colorless oil.

Source