Boron trifluoride → (Z)-(5R)-9-(tetrahydro-pyran-2-yloxy)-1-trimethylsilanyl-non-2-en-7-yn-5-ol

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Reaction Steps

24.5 ml (174 mmol) of Tetrahydro-2-(2-propynyloxy)2H-pyran was dissolved in 285 ml of abs. THF and deprotonated at -13°--6° by adding slowly 112 ml of nBuLi (1.55 M, hexane). 20 Minutes later, the solution was cooled to -75° and 21.85 ml of BF3 oEtOEt was added. Afterwards, 10.51 g of (Z)-(R)-trimethyl-(4-oxiranyl-but-2-enyl)-silane, dissolved in 96 ml of abs. THF, was added within 75 minutes while maintaining the temperature below -70°. The reaction mixture was kept for another 50 minutes at this temperature and then poured onto crushed ice/NaHCO3, extracted with ether, washed with brine, dried over sodium sulfate and evaporated to dryness. Flash chromatography (SiO2, hexane/AcOEt=8/2) produced 17.83 g of (Z)-(5R)-9-(tetrahydro-pyran-2-yloxy)-1-trimethylsilanyl-non-2-en-7-yn-5-ol as colorless oil (1:1 epimeric mixture).

Provenance & Evidence