Aluminium lithium hydride → (2-Isopropyl-furan-3-yl)-methanol

A solution of 2-isopropyl-furan-3-carboxylic acid ethyl ester (82) (4.0 g, 21.95 mmoles) in tetrahydrofuran (70 ml) was treated portionwise during 0.5 h with lithium aluminium hydride (0.7 g, 18.4 mmoles) under a nitrogen atmosphere. When the addition was complete the mixture was stirred at room temperature for 18 hours, then quenched by the addition of excess acetone (1 ml) and then water (1 ml). After diluting with ethyl acetate (150 ml) the grey precipitate was removed by filtration. The filtrate was evaporated and the residue dissolved in diethyl ether and dried. Evaporation of the solvent afforded (2-isopropyl-furan-3-yl)-methanol. This material was used immediately in the next step. (ii) A solution of the (2-isopropyl-furan-3-yl)-methanol from (i) in dry dichloromethane (120 ml) was treated with chloro-tri-isopropyl-silane (5.2 g, 27.0 mmoles) and imidazole (3.0 g, 44.0 mmoles) and the mixture was stirred overnight at room temperature. The reaction mixture was washed sequentially with 2M aqueous hydrochloric acid, water, saturated aqueous sodium bicarbonate, water and brine. After drying, evaporation of the solvents afforded a colourless oil, which heated at 125° C. under reduced pressure (10 millibars). The residue was compound 83 obtained as a pale yellow oil.