| 摘要 |
A process for the halogenation of activated methylene and methine compounds with at least equimolar amounts of an electrophilic halogenation reagent, which comprises reacting said activated methylene and methine compounds in the presence of catalytic amounts of a titanium compound of the formula I or of a titanium compound of the formula II <paragraph lvl="0"><in-line-formula>R1TiX1X2X3 (I), </in-line-formula><paragraph lvl="0"><in-line-formula>R2R3TiX1X2 (II), </in-line-formula>in which R1 is chlorine, bromine or iodine, a substituted or unsubstituted cyclopentadienyl or indenyl, and X1, X2 and X3 are, independently of one another, chlorine, bromine or iodine, or X1, X2 and X3 are an organic sulfonate group where R1 is a substituted or unsubstituted cyclopentadienyl or indenyl; R2 and R3 are a substituted or unsubstituted cyclopentadienyl or indenyl, R2 and R3 together are a substituted or unsubstituted and bridged or unbridged biscyclopentadienyl or bisindenyl, or R2 and R3 together are a substituted or unsubstituted 1,3-, 1,4- or 1,5-diolate, and X1, and X2 are, independently of one another, chlorine, bromine or iodine or an organic sulfonate group. If the diolate is enantiopure, the process is enantioselective on use of racemic activated methine compounds.
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