Thionyl Chloride → 2-(Benzyloxy)-4-(chloromethyl)-1-methoxybenzene

Beteiligte Stoffe

Reaktionsschritte

Thionyl chloride (64 ml) was added over 10 minutes to a stirred solution of the above alcohol in dichloromethane (500 ml). After 20 minutes the mixture was evaporated to dryness, in vacuo, toluene (2×75 ml) added, and evaporation in vacuo repeated to give crude 3-benzyloxy-4-methoxy-benzyl chloride (97.85 g, 105.5%). The chloride (353 mmole) was dissolved in acetone, (400 ml) treated with sodium thiocyanate, (57.22 g ,706 mmole) homogenized and heated under reflux for 1.5 hours. The solid was filtered off at room temperature and the solvent evaporated in vacuo. The residue was suspended in water (600 ml) to give a solution of pH 2, and neutralized with sodium bicarbonate solution. After crystallization the solid was collected, dried, dissolved in dichloromethane (300 ml) , dried (Na2SO4), treated with charcoal, filtered and evaporated to dryness. The residue was crystallized from petroleum ether (400 ml) to give 3-benzyloxy-4-methoxy-benzyl thiocyanate (95.65 g, 95.0%), mp 70-74° C. The thiocyanate (335 mmole) was heated under reflux in n-valeronitrile (280ml) for 2 hours and evaporated to dryness to give 98.4 g of crude product. This was dissolved in THF (200 ml) and treated with 32% aqueous ammonia solution (101 ml) at room temperature. After 3 hours the thiourea was collected at 10° C. and washed with diethyl ether to give 1-(3-benzyloxy-4-methoxy-benzyl)-2-thiourea (63.08 g, 62.2%), mp 179-181° C. The filtrate was evaporated to dryness and the residue crystallized from dichloromethane to give 11.51 g (11.3%) as a second crop.

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