Tetrahydrofuran → HCID 59201437, compound

Participants

Reaction Conditions

Reaction Steps

The (S)-tert-butyl 4-((R)-5-(cyclohexyloxy)-5-oxo-2-(tosyloxymethyl)pentyl)-2,2-dimethyloxazolidine-3-carboxylate (309 mg, 0.545 mmol, 1.0 equiv) was dissolved in 17 mL of THF and the solution cooled to 0° C. Methylmagnesiumbromide (3.0 M in THF, 1.64 mL, 3.0 equiv) was added via syringe. LC/MS analysis showed ca 15% conversion to the mono-tosylate. An additional 0.55 mL of MeMgBr solution was added and the mixture warmed to ambient and stirred overnight. LC/MS analysis showed complete conversion to the mono-tosylate. The mixture was heated to reflux for 24 hr. After this time, complete conversion to the cyclised product was observed. The mixture was cooled to ambient and quenched with water. The layers were separated and the organic layer washed with brine, dried over Na2SO4, filtered and evaporated. The pyran derivative was purified by flash chromatography on silica, (12 g), eluting with 0-41% EtOAc in hexanes. This afforded 138 g (78% yield) of (S)-tert-butyl 4-(((R)-6,6-dimethyl-tetrahydro-2H-pyran-3-yl)methyl)-2,2-dimethyloxazolidine-3-carboxylate as a clear syrup. MS ESI +ve m/z 350 (M+Na).

Provenance & Evidence