Sulfuric Acid → (2R,3R)-3-(1,2-dihydroxypropyl)-1,4-dioxaspiro[4,5]decane-2-carboxaldehyde

Participants

Reaction Conditions

Reaction Steps

A slurry of copper sulfate (175 g, 1.09 mol, 2 eq) and rhamnose hydrate (100 g, 0.55 mol) in freshly distilled cyclohexanone (330 g) was stirred under nitrogen as concentrated sulfuric acid (1.5 mL) was added at once. The reaction mixture was warmed to about 29° C. internal. The reaction mixture was allowed to stir overnight. The reaction was analyzed by TLC (ethyl acetate) and was complete. The reaction mixture was filtered through a pad of celite and the solid was washed with ethyl acetate. The filtrate was treated with about 1.5 mL of concentrated ammonium hydroxide to pH 7, and the resulting solid was removed by filtration. The filtrate was concentrated under reduced pressure to give a colorless oil. The residue was dissolved in ether and treated with hexane and allowed to stand overnight. Resulting solid was isolated by filtration and dried to give 92.3 g (0.31 mol, 57%) of (2R,3R)-3-(1,2-dihydroxypropyl)-1,4-dioxaspiro[4,5]decane-2-carboxaldehyde, as an off-white solid: [α]D=+0.457 (10.485 mg/cc MeOH); 1H NMR (CDCl3) δ 1.34 (d, 3H), 1.40 (m, 2H), 1.6 (m, 8H), 2.78 (d, 1H), 3.0 (s, 1H), 3.9 (m, 1H), 4.07 (m, 1H), 4.6 (d, 1H), 4.9 (m, 1H), 5.4 (s, 1H) ppm.

Provenance & Evidence