| 摘要 |
1. A process for preparing a 2-(thiosubstituted)-4-haloacetophenone which comprises reacting 2,4-dihaloacetophenone with a thiolating agent under substantially anhydrous conditions in which the volume of water present is less than about 1 percent. 2. A process according to claim 1 in which the reaction is performed in the presence of a base. 3. A process according to claim 1 or 2 in which the volume of water present is from about 0.01 to about 0.5%. 4. A process according to any preceding claim in which the reaction is performed in an ether solvent. 5. A process according to claim 4 in which the ether solvent is selected from tetrahydrofuran, diisopropyl ether, tert-butyl methyl ether or diethyl ether. 6. A process according to any preceding claim in which a 2-(thiosubstituted)-4-haloacetophenone is a compound of formula (I): wherein R<1> is C1-6 alkyl, or phenyl which is unsubstituted or substituted by from one to five groups which are the same or different selected from the group consisting of halogen, C1-6 alkyl, C1-6 haloalkyl, C1-6 alkoxy, C1-6 haloalkoxy and -S(O)nR<5>; R<2> is hydrogen, halogen, C1-6 alkyl, C1-6 haloalkyl, C1-6 alkoxy, C1-6 haloalkoxy or --S(O)nR<5>; R<3> is halogen; n is zero, one or two; R<5> is C1-6 alkyl or phenyl which is unsubstituted or substituted by from one to five groups which are the same or different selected from the group consisting of halogen, C1-6 alkyl, C1-6 haloalkyl, C1-6 alkoxy, C1-6 haloalkoxy and --S(O)n -alkyl; 2-(thiosubstituted)-4-haloacetophenone is a compound of formula (I): wherein R<2> and R<3> are as defined above and R<4> is halogen; and a thiolating agent of formula (III): R<1>S-X (III) wherein R<1> is as defined above and X is hydrogen or a metal cation; 7. A process according to claim 6 in which R<2> is selected from hydrogen, halogen, C1-6 alkoxy or C1-6 haloalkoxy. 8. A process according to claim 6 in which R<3> and R<4> are halogen and R<2> is hydrogen. 9 A process according to claim 6, 7 or 8 in which X is hydrogen or an alkali metal cation. 10. A process according to claim 6, 7 or 8 in which R<1> is C1-6 alkyl. 11. A process according to any preceding claim in which the reaction is performed at a temperature from -80 degree C. to the boiling point of the solvent, preferably from -20 degree C to 60 degree C. 12. A process according to any preceding claim in which the molar ratio of the 2,4-dihaloacetophenone : thiolating agent is from 1:1 to 1:2, preferably from 1:1 to 1:1.5. |
