Thionyl Chloride → (E)-4,4-dimethyl-2-pentenoyl chloride

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Reaction Steps

To a solution of (E)-4,4-dimethyl-2-pentenoic acid (Gream, G. E.; Serelis, A. K. Aust. J. Chem. 1978, 31, 863) (200 mg, 1.6 mmol) in benzene (10 ml) was added thionyl chloride (0.5 ml) and the mixture was heated to reflux for 60 min. Volatiles were removed by evaporation to give crude (E)-4,4-dimethyl-2-pentenoyl chloride. Free base of the titled compound was prepared from N-(2-pyridyl)-o-phenylenediamine (150 mg, 0.81 mmol) and (E)-4,4-dimethyl-2-pentenoyl chloride obtained as above according to the preparation of (E)-1-(2-pyridyl)-2-styryl-1H-benzimidazole (Example 1, method A). The free base was dissolved with a 10% methanol solution of hydrogen chloride (5 ml). Concentration and recrystallization from ethyl acetate yielded the titled compound. MW: 313.83; mp: 171.0-172.3° C.; 1H-NMR (CDCl3) δ: 8.86-8.82 (1H, m), 8.27 (1H, d, J=16.3 Hz), 8.21-8.13 (2H, m), 7.72-7.65 (1H, m), 7.62-7.43 (4H, m), 6.31 (1H, d, J=16.3 Hz), 1.17 (9H, s).

Provenance & Evidence