Functionalization ferrocenyl intermediates

Between the two synthetic schemes, the amidoxime route appears to be the most used and reliable strategy. For instance, oxadiazole systems involved as organometaUic Hgands can be synthesized by precursors already including the complexed metal, such as in the case of ferrocenyl oxadiazoles 18 (2014JOM-C67). The latter is produced from ferrocenyl substituted prop-argyl aldehyde 15 which, after O-functionalization into intermediate 16, undergoes an intramolecular Michael addition into oxadiazoline 17, before elimination of acetaldehyde to yield final product 18 (Scheme 5). 

The synthesis of ferrocene 9 relied on chemistry introduced by Sammakia, Uemura, and Richards [18]. They had shown that 2-ferrocenyl oxazoline 10 derived from t-leucine could be selectively deprotonated and trapped with electrophiles to afford ortho-functionalized planar-chiral products 11 with excellent diastereoselectivities (Scheme 2.1.2.3). Following this strategy, 9 became accessible in a highly straightforward manner by trapping the lithiated intermediate derived from 10 with benzophenone [10, 11],... 

In poly(methylphenylphosphazene), [Ph(Me)P=N] 58, both the phenyl and methyl substituents are potential sites for formation of derivatives [65]. Deprotonation of ca. half of the methyl substituents on this polymer was carried out in THF at — 78 °C using n-BuLi. On treatment of the intermediate polymer anion with ferrocenyl ketones and subsequent quenching with a mild proton source, phos-phazenes 59 containing the OH functional group were prepared. The amount of substitution, determined by NMR and elemental analysis, was found to be 45 and 36%, respectively, for polymers 59a and 59b (Scheme 10-27). For these substituted polymers was 187000 and 154000, respectively, and no degradation of the parent polymer occurred. 

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