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|Title:||Synthetic approaches to a hypervalent trigonal bipyramidal carbon species and a versatile reagent for the oxidation of primary and secondary alcohols to aldehydes and ketones|
|Author(s):||Henderson, Craig Conger|
|Doctoral Committee Chair(s):||Deuman, Scott E.|
|Department / Program:||Chemistry|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||The synthesis of a novel ortho-bridged triarylmethanol, 6-(1,1-dimethylethyl)-12c-hydroxy-4,8-dioxa-4H,8H-dibenzo- (cd,mn) pyren-12(12cH)-one, is described in Part I. The key step involves an intramolecular Friedel-Crafts reaction of a triarylmethyl cation. Some reactions of this methanol derivative are presented as part of an attempted synthesis of a hypervalent (10-C-5) trigonal bipyramidal carbon species.
Other approaches to a hypervalent trigonal bipyramidal carbon species from spiro (anthracene-9,1$\sp\prime$-phthalan) derivatives are presented in Part II. The electronic and geometric factors of the ligands in the target hypervalent carbon species are discussed in terms of known ligand-induced stabilization of hypervalent species of higher row main group elements. Stabilization of the hypervalent bond by delocalization of the excess electron density in the three-center, four-electron (3c-4e) bond onto a bidentate $\pi$-acceptor ligand in the equatorial plane of the trigonal bipyramidal 10-C-5 species is emphasized. The synthesis and reactions of the spiro (anthracene-9,1$\sp\prime$-phthalan) precursors is given along with a summary of the attempts to convert these precursors to hypervalent 10-C-5 species. The synthetic value of a mercuration/halogenation reaction for the regiospecific addition of an iodine to an arene is illustrated in the synthesis of one of the precursors, a novel ortho-bridged triarylmethyl trifluoromethylsulfonate.
Another example of the mercuration/halogenation reaction of an arene is given in Part III which describes the large scale synthesis of 4-(1,1-dimethylethyl)-2-iodobenzoic acid, the precursor to 1,1,1-tris(acetoxy)-6-(1,1-dimethylethyl)-1,1-dihydro-1,$ 2$-benziodoxol-3(1H)-one. The use of this 12-I-5 triacetoxyperiodinane, which is a derivative of the so-called Dess-Martin Periodinane, as a reagent for the oxidation of primary and secondary alcohols to aldehydes and ketones is also described. The advantages of the tert-butylated triacetoxyperiodinane compared to the unsubstituted Dess-Martin triacetoxyperiodinane are discussed in terms of ease of preparation, increased solubility, and decreased rate of decomposition of the 10-I-4 iodinane oxide precursor at its melting point. Several examples of oxidations of alcohols with 12-I-5 triacetoxyperiodinanes and 10-I-4 iodinane oxides are given, and a possible mechanism for these reactions is discussed.
|Rights Information:||Copyright 1991 Henderson, Craig Conger|
|Date Available in IDEALS:||2011-05-07|
|Identifier in Online Catalog:||AAI9210835|