Diisobutylaluminum hydride → (3',4'-Dihydro-1'H-spiro[[1,3]dioxolane-2,2'-naphthalen]-8'-yl)methanol

Participants

Reaction Steps

To a round bottom flask containing methyl 3′,4′-dihydro-1′H-spiro[[1,3]dioxolane-2,2′-naphthalene]-8′-carboxylate (19-2) (1.88 g, 7.57 mmol) was added anhydrous THF (15 ml). The reaction mixture was then cooled to 0 C (ice water bath) while stirring under N2. Then added DIBAL-H (24 mL, 24.00 mmol) dropwise over 10 minutes with stirring. Stirred at 0 C for 10 minutes, then permitted to warm to room temperature. Followed by LC/MS. Stirred overnight at room temperature, noticed there was still some starting material so cooled back to 0 C, then added additional DIBAL-H (19 mL, 19.00 mmol) & after 10 minutes warmed to room temperature. The reaction mixture was cooled to 0 C (ice water bath), then quenched by slow dropwise addition of saturated Rochelle's Salt (Na+/K+ Tartrate) (lots of bubbling so add slowly), then stirred for an hour to help break up/solubilize the emulsion; then suspended in EtOAc, filtered emulsion (gooey material, very little desired product by LC/MS); organics separated, then washed with saturated Rochelle's salt again then washed with saturated NH4Cl, then with saturated NaHCO3, then H2O, then brine; organics dried over sodium sulfate, filtered & concentrated. Purification by silica gel chromatography (30-100% EtOAc/Hex; 80 g ISCO); desired fractions concentrated to yield (3′,4′-dihydro-1′H-spiro[[1,3]dioxolane-2,2′-naphthalen]-8′-yl)methanol (19-3). HRMS [M+Na] calculated; 243.0992, observed; 243.0990.

Provenance & Evidence