Alkoxide attack oil coordinated olefin can be reversible
Alkoxide attack oil coordinated olefin can be reversible
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DOI：
10.1021/om950905z
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发表时间：
1996-04-02
期刊：
影响因子：
2.8
通讯作者：
Caulton, KG
中科院分区：
文献类型：
--
作者：
Hauger, BE;Huffman, JC;Caulton, KG
醇盐 (MeO(-), EtO(-), (PrO-)-Pr-i) 在 CH2Cl2 中的 Ir(Tripod)(COD) (Tripod = MeC(CH(2)PPh(2))(3), COD = 1,5-cyclooctadiene) 的配位烯烃上发生攻击，得到 Ir(Tripod)(2-alkoxycyclooct-5-en-1-yl)，主要作为外切异构体。这些产物缓慢消除醇，得到 Ir(Tripod)((1,2-eta(2))-6-sigma-cycloocta-1,4-dienyl)，这是当醇盐为 (t)BuO(-) 时检测到的唯一产物。将过量的甲醇添加到外型-Ir(Tripod)(2-甲氧基环辛-5-en-1-基)中会抽象出MeO(-)（即异裂O-C键断裂），因此氢键溶剂逆转了对配位烯烃的亲核攻击。醇盐（MeO(-)、(PrO-)-Pr-i、(t)BuO(-) 和 2-BuO(-)）在 Rh(Tripod)(NBD)(+)（NBD = 降冰片二烯）的烯属碳上发生加成，得到 Rh(Tripod)(2-alkoxynorborn-4-en-1-yl)。外型/甲氧基实例的晶体结构已确定。虽然该产品不能单分子消除醇，但在添加或不添加 NBD 的情况下尝试质子化降冰片基醚并未成功。再次，酸从配体醚中夺取RO(-)。
Alkoxide (MeO(-), EtO(-), (PrO-)-Pr-i) attack occurs at the coordinated olefin of Ir(Tripod)(COD) (Tripod = MeC(CH(2)PPh(2))(3), COD = 1,5-cyclooctadiene) in CH2Cl2 to give Ir(Tripod)(2-alkoxycyclooct-5-en-1-yl), primarily as the exo isomer. These products slowly eliminate alcohol to give Ir(Tripod)((1,2-eta(2))-6-sigma-cycloocta-1,4-dienyl), which is the only product detected when the alkoxide is (t)BuO(-). Addition of excess methanol to exo-Ir(Tripod)(2-methoxycyclooct-5-en-1-yl) abstracts MeO(-) (i.e., heterolytic O-C bond cleavage), and thus a hydrogen-bonding solvent reverses the nucleophilic attack on coordinated olefin. Alkoxide (MeO(-),(PrO-)-Pr-i, (t)BuO(-) and 2-BuO(-)) addition occurs at an olefinic carbon of Rh(Tripod)(NBD)(+) (NBD = norbornadiene) to give Rh(Tripod)(2-alkoxynorborn-4-en-1-yl). The crystal structure of the exo/methoxy example has been determined. While this product cannot unimolecularly eliminate alcohol, attempts to protonate the norbornyl ether in the presence or absence of added NBD were not successful. Here again, acid abstracts RO(-) from the ligand ether.