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oai:www.ideals.illinois.edu:2142/34371 2023-07-10 col_2142_5131 col_2142_14789 com_2142_5130 com_2142_14788 com_2142_8903

Hartwig, John F. Hartwig, John F. Girolami, Gregory S. Rauchfuss, Thomas B. Burke, Martin D. Madrahimov, Sherzod 2012-09-18T21:13:45Z 2012-09-18T21:13:45Z 2012-08 2012-09-18T21:13:45Z 2012-08 Mechanistic studies on iridium catalyzed allylic substitution reactions catalyzed by iridium phosphoramidite complexes revealed that the active catalyst is generated through a base assisted cyclometalation of the phosphoramidite to form five-membered iridacycle. A mechanism for the reaction was proposed based on a series of kinetic experiments. According to this mechanism the product bound cyclometalated complex is the resting state of the catalyst. First examples of allyliridium complexes containing cyclometalated phosphoramidite ligand were prepared. A series of stoichiometric experiments showed that these allyliridium complexes were chemically and kinetically competent to be intermediates in iridium catalyzed allylic substitution reactions. Double inversion mechanism for the iridium catalyzed allylic substitution reaction was also shown through a combination of catalytic and stoichiometric reactions of cyclometalated iridium complexes. A series of kinetic studies also showed that oxidative addition was the enantiodetermining step in iridium catalyzed allylic substitution. Finally, allyliridium complexes containing cyclometalated triphenylphosphite ligand were prepared. These complexes were competent to be intermediates in non-stereoselective allylic substitution reactions catalyzed by iridium triphenylphosphite complexes. A series of kinetic experiments showed that regioselectivity of iridium catalyzed allylic substitution is likely controlled by a larger binding affinity of terminal alkenes to iridium center over internal disubstituted alkenes. Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2012-06-07T19:31:52Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 1 Sherzod_Madrahimov.pdf: 5043323 bytes, checksum: 3f88ac128c398fd3ecf40bb7ff0b5199 (MD5) Made available in DSpace on 2012-09-18T21:13:45Z (GMT). No. of bitstreams: 2 Sherzod_Madrahimov.pdf: 5041932 bytes, checksum: c000dd2b0b70329487f642fe3938b6a0 (MD5) license.txt: 4068 bytes, checksum: 26536778a2445ff24cf294c7859ed4c5 (MD5) http://hdl.handle.net/2142/34371 en Copyright 2012 Sherzod Madrahimov allylic substitution mechanistic studies iridium catalyzed Mechanistic studies on iridium catalyzed allylic substitution Chemistry 1413 Chemistry 0335 University of Illinois at Urbana-Champaign Dissertation Ph.D. PHD:Chemistry -UIUC 10KS0335PHD