Dimethyl Sulfoxide → 3-(Pyridin-2-YL)propanal

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Reaction Steps

Dimethyl sulphoxide (3.3 ml) was added dropwise to a solution of oxalyl chloride (3.9 ml) in dichloromethane (25 ml) at -78° under nitrogen. After gas evolution had ceased (5 min) a solution of 2-pyridinepropanol (4.0 g) in dichloromethane (20 ml) was added over 5 min and the solution stirred at -78° for 20 min. Triethylamine (5 ml) was added dropwise to the solution, then the resulting dark green mixture warmed to 20° and washed with 2M sodium carbonate solution (20 ml). The organic phase was dried and evaporated in vacuo to give 2-pyridinepropanal. This aldehyde was immediately dissolved in THF (30 ml) and added dropwise to a 3M solution of methylmagnesium chloride in THF (20 ml) at 0°-5° under nitrogen. After 1 h, water (10 ml) was cautiously added followed by sufficient 2M hydrochloric acid to dissolved all the magnesium residues (resulting pH~7 ). The solution was extracted with dichloromethane (3×30 ml) and the organic extracts dried and evaporated in vacuo to a dark oil. Kugelrohr bulb to bulb distillation (b.p. 130°-135°/0.7 mm) afforded the title compound as a pale yellow oil (0.91 g), t.l.c. ethyl acetate Rf 0.17.

Provenance & Evidence