Dimethylformamide → 1,3-Benzothiazole-2-carbaldehyde

Participants

Reaction Conditions

Reaction Steps

A solution of freshly distilled (b.p. 82° C., 2 torr) benzothiazole (10 g, 0.074 mole) in 250 ml tetrahydrofuran was cooled under nitrogen to -78° C. and stirred at this temperature for 15 minutes. To this was added dropwise over 15 minutes 29.6 ml (0.074 mole) 2.5M n-butyllithium, stirring continued for 25 minutes, and 8.6 ml (0.111 mole) dimethylformamide was added and the reaction mixture stirred for an hour. The mixture was allowed to warm to room temperature, 200 g ice was added and the solvent evaporated in vacuo. The aqueous residue was extracted with 5×100 ml ethyl acetate, the extracts dried (MgSO4), concentrated to a small volume and chromatographed on a silica gel column, eluting with 96:4 chloroform/ethyl acetate to yield 8.4 g of the desired aldehyde, m.p. 74.5°-75° C. 1H--NMR(CDCl3)ppm (delta): 7.54 (m, 2H), 7.97 (m, 1H), 8.21 (m, 1H), 10.1 (s, 1H).

Provenance & Evidence