Alkoxide Attack on Coordinated Olefin Can Be Reversible

Autor:	Bryan E. Hauger, and John C. Huffman, Kenneth G. Caulton
Rok vydání:	1996
Předmět:	Olefin fiber Chemistry Stereochemistry Norbornadiene Organic Chemistry Tripod (photography) Ether Heterolysis Medicinal chemistry Inorganic Chemistry chemistry.chemical_compound Nucleophile Alkoxide Physical and Theoretical Chemistry Bond cleavage
Zdroj:	Organometallics. 15:1856-1864
ISSN:	1520-6041 0276-7333
DOI:	10.1021/om950905z
Popis:	Alkoxide (MeO-, EtO-, iPrO-) attack occurs at the coordinated olefin of Ir(Tripod)(COD) (Tripod = MeC(CH2PPh2)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-η2)-6-σ-cycloocta-1,4-dienyl), which is the only product detected when the alkoxide is tBuO-. 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-, iPrO-, tBuO- 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, ac...
Databáze:	OpenAIRE
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