Stereoselective 5-exo radical and Heck cyclizations of axially chiral o-iodoanilides to enantioenriched oxindoles and dihydroindolones are described. Mechanisms for the transfer of
chirality from the atropisomeric anilides to the newly formed stereocenters in the cyclic products are proposed and supported with physical data. Additionally, the N-aryl bond rotation barriers for eight o-iodoanilides are reported.
A series of axially chiral N-allyl-o-iodoanilides were cyclized under room temperature radical conditions to dihydroindolones with good to excellent chirality transfer (7497 %). Cyclization
rate constant data is presented to rationalize the regioselective preference for N-allyl over N-acryloyl cyclization when an
o-methyl group is present. X-ray crystallography was used to
assign absolute configurations to a cyclization precursor/product pair. Radical 5-exo cyclizations of axially chiral
o-iodoanilides bearing branched, bulky N-substituents are covered. The bulkiness of N-substituents permitted the resolution of a series of novel o-iodoanilides lacking a second ortho substituent. Radical cyclizations of these o-iodoanilides transferred this transient axial chirality into a new stereocenter in the oxindole products with high fidelity (7892 %). The first Heck cyclizations of axially chiral o-iodoanilides with chirality transfer (8489 %) are described. X-ray crystallographic data is presented for one anilide cyclization precursor with studies to elucidate the mechanism of chiral transfer.
Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-11292005-113044 |
Date | 20 March 2006 |
Creators | Lapierre, Andre Joseph Benjamin |
Contributors | Prof. Michael Mokotoff, Prof. Theodore Cohen, Prof. Kay Brummond, Prof. Dennis Curran |
Publisher | University of Pittsburgh |
Source Sets | University of Pittsburgh |
Language | English |
Detected Language | English |
Type | text |
Format | application/pdf |
Source | http://etd.library.pitt.edu/ETD/available/etd-11292005-113044/ |
Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Pittsburgh or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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