教案-金属有机化合物的基元反应.ppt

金属有机化合物的基元反应 一般有四类基元反应 1 配体的配位和解离反应 2 氧化加成反应和还原消除反应 3 插入反应和消除反应（反插入反应） 4 和金属络合的配体被进攻的反应 插入反应与反插入反应 插入反应为不饱和键插入到M-H,M-C之间的反应。它主要有两种类型：1 AB分子插入后分别与金属和R基团相连。2 AB分子插入后A同时与金属和R基团相连 Definitions; Migratory Insertion - MI Numbering describes which atoms of the inserted ligand are bonded to M and X after the insertion Opposite of insertion is elimination (or “deinsertion” in USA) Definitions; Elimination - E This is the same as the last slide with arrows going backwards Named by which atom contains the migrating group Unfortunately the term “1,1-elimination” etc. is rarely used, even though it’s the opposite of a 1,1-insertion! 1,1-Migratory Insertion and a-Elimination Stereochemistry at carbon Configuration at a stereogenic carbon is retained Same applies to the reverse, i.e. a-elimination CO的插入反应: 1,1-Migratory Insertion and a-Elimination Mechanistic questions The above reaction has been studied in detail, and much is known about the mechanism 研究表明是按R基团迁移的的途径进行的R基团迁移不可能得到4，研究表明产物1：2：3的比率为1：2：1，而且没有4 生成。 1,1-Migratory Insertion and a-Elimination Where does the CO come from? CO that is inserted into Mn-Me bond is “unlabelled”, so it must have come from within the complex (i.e. mechanism is intramolecular) The 13CO in the product has remained cis to acyl and has not moved at all to the trans site. In other words, the reaction is under kinetic control (I.e. the first-formed product is observed). 1,1-Migratory Insertion and a-Elimination Is this a cis process? The 13C labelled acyl product was synthesised by an alternative route shown above, and was then heated to promote elimination Only the cis isomer was observed, therefore in the reverse reaction (the 1,1-MI) the methyl group must be reacting with a CO that is cis to it. This logic relies on the Principle of Microscopic Reversibility… In a single step reversible reaction, the mechanism of the forward reaction is the same as that of the reverse reaction 1,1-Migratory Insertion and a-Elimination Which Move