Water → 3-Chloro-1,8-naphthyridine-4-carbaldehyde

Participants

Reaction Conditions

Reaction Steps

3-Chloro4-methyl-[1,8]naphthyridine (3.0 g, 16.7 mmol) from Step 3 was dissolved in 4:1 dioxane:water (30 mL) and selenium dioxide (5.9 g, 50.4 mmol) was added. The reaction mixture was heated (110° C.) for 2.5 h, cooled to RT, poured into satd. aq. NaHCO3 (30 mL) and water (10 mL). The mixture was subsequently treated with DCM (80 mL) and the solids filtered off through Celite and rinsing the filter cake with DCM. After separating the aqueous and organic layers, the aqueous phase was re-extracted with DCM (4×80 mL) and the combined organics were dried (Na2SO4) and concentrated. The crude product was chromatographed by SGC (MeCN eluant) to yield the title compound 3-chloro-[1,8]naphthyridine-4-carbaldehyde (1.0 g, 5.2 mmol). Note: owing to weak UV activity, it was found more efficacious to monitor column fractions with MS rather than UV, as in Step 3. MS (ESI+) for m/z 193 (M+H)+. 1H NMR(CDCl3)δ 10.79 (s, 1H), 9.28 (dd, 1H), 9.17 (s, 1H), 9.14 (dd, 1H), 7.63(dd. 1H).

Provenance & Evidence