| 摘要 |
Process for preparing an S-substituted isothiourea having the functional group <IMAGE> in which R<1> represents an optionally substituted alkyl, alkenyl, aryl or aralkyl group, by reacting a thiourea containing the functional group <IMAGE> with an α-activated etherifying agent of the formula X-A-Y, where X represents a halogen atom, A is a direct linkage or CH2, and Y is an electron-withdrawing group, to give a thioether <IMAGE> and reacting the ether, in a second step, with a compound of the formula R<1>SH. The process is particularly well suited to preparing the known herbicide <IMAGE> from the corresponding thiourea by, in the first step, using chloroacetic acid to form the S- carboxymethylisourea, which is then subjected to an exchange reaction with ethanethiol. This thereby results in a higher total yield and/or a higher economic advantage as compared with known processes.
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