Reaktion #50176

Reaktionsgleichung

Tetrahydro-2-(2-propynyloxy)-2H-pyran

tetrahydro-4H-pyran-4-one

ethyl magnesium bromide

→

4-hydroxy-4-[3-(tetrahydropyran-2-yloxy)prop-1-ynyl]tetrahydropyran

Ausbeute 88.3%

Lösungsmittel

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   SonstigeThe reaction was quenched by addition of crushed ice and saturated aqueous NH4Cl
2. 2
   ExtraktionThe resulting two-layered mixture was extracted with ether (3×150 mL)
3. 3
   TrocknenThe combined organic layers were dried over MgSO4
4. 4
   Filtrationfiltered
5. 5
   Einengenconcentrated in vacuo
6. 6
   SonstigePurification by chromatography on silica gel (200 g, 20% ethyl acetate: hexanes)

Vorschrift

Tetrahydro-2-(2-propynyloxy)-2H-pyran (21 g, 150 mmol) was converted to the corresponding magnesium anion by deprotonation with ethyl magnesium bromide (75 mL of a 2M solution, 150 mmol) according to the method described in Org. Synth., 60: 81, 7 (1981). The resulting anion was cooled to -20° C. and tetrahydro-4H-pyran-4-one (14.8 g, 148 mmol) in dry THF (30 mL) was added dropwise and the resulting solution stirred for three hours. The reaction was quenched by addition of crushed ice and saturated aqueous NH4Cl. The resulting two-layered mixture was extracted with ether (3×150 mL). The combined organic layers were dried over MgSO4, filtered, and concentrated in vacuo. Purification by chromatography on silica gel (200 g, 20% ethyl acetate: hexanes) provided 4-hydroxy-4-[3-(tetrahydropyran-2-yloxy)prop-1-ynyl]tetrahydropyran(31.4 g, 88%).

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