Thionyl Chloride → 2-(3-Methoxy-4-methyl-phenyl)vinylisocyanate

Participants

Reaction Steps

3-(3-Methoxy-4-methylphenyl)propenoic acid (5.33 g, 27.7 mmol) (prepared according to the procedure described in J. Med. Chem. 1991, 34, 1662-1668) is suspended in benzene (30 mL) and treated dropwise with thionyl chloride (2.22 mL, 30.5 mmol) at 0° C. The reaction is heated to reflux and it is maintained for 1 hour. The volatiles are removed in vacuo and the resulting solid is dissolved in dioxane and added dropwise to a mixture of sodium azide (3.6 g, 55.4 mmol) in water/dioxane (30 mL, 1:5) at 0° C. After stirring 1 hours, the solution is poured over ice-water, the precipitate is collected and washed with water. The solid is dried under vacuum over P2O5 (24 hours), dissolved in benzene (30 mL) and heated to reflux slowly over about 4 hours. The benzene is removed to give 2-(3-methoxy-4-methyl-phenyl)vinylisocyanate as a brown oil. The oil is taken up in o-dichlorobenzene, treated with iodine and heated to reflux for 3.5 hours. The volatiles are removed and the residue is mixed with 2.5% MeOH/CH2Cl2(10 mL), then allowed to stand overnight at room temperature. The resulting solid is collected washed with hexane and ether, and dried to give the title compound (2.67 g, 14.1 mmol).

Provenance & Evidence