2,2-Dimethoxypropane → 2-(2,2-Dimethyl-1,3-dioxan-5-yl)ethanol

Participants

Reaction Steps

To a suspension of lithium aluminium hydride (2.87 g, 76 mmol) in tetrahydrofuran (125 ml), a solution of triethyl 1,1,2-ethanetricarboxylate (9.2 ml, 9.85 g, 40 mmol) in tetrahydrofuran (25 ml) was added dropwise with stirring over 2 hours. Excess reagent was then quenched with aqueous tetrahydrofuran (1:2). The inorganic salts were filtered off and washed with ethanol (100 ml). The filtrate and washings were combined and the solvent was evaporated under reduced pressure to afford a colourless oil (4.85 g). To a suspension of this oil in acetone (100 ml), 2,2-dimethoxypropane (25 ml) and p-toluenesulphonic acid monohydrate (2.3 g, 12 mmol) were added and the mixture was stirred for 1 hour. The resulting solution was neutralised with Amberlite IR 45 (OH− form, methanol washed), filtered and the solvent evaporated under reduced pressure. The residue was purified by column chromatography on silica gel, eluting with chloroform-methanol mixtures (40:1 and 25:1) to afford 5-(2-hydroxyethyl)-2,2-dimethyl-1,3-dioxan as a colourless liquid (3.01 g, 47%); νmax (film) 3420, 2940, 1375, 1200 and 1080 cm−1; δH (CDCl3) 1.34-1.70 (8H, m, C(CH3)2 and CH2CH2OH), 1.7-2.1 (1H, m, CH), 2.15 (1H, br, D2O exchangeable, OH), and 3.5-4.0 (6H, m, 3×CH2O); (Found: C, 58.33; H, 10.11%. C8H16O3 0.25H2O requires C, 58.34; H, 10.10%. [M−CH3]+ found 145.0864; C7H13O3 requires 145.0865).

Provenance & Evidence