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|Title:||Use of the Cyclopropylcarbinyl - Allylcarbinyl Rearrangement as a Probe of the Thiophilic Addition Reaction Mechanism|
|Author(s):||Garrett, Curtis Gene|
|Department / Program:||Chemistry|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||The mechanism of thiophilic addition was examined using the reported ring opening rearrangements of cyclopropylcarbinyl species as a probe to determine whether the reaction proceeds in a one or two electron fashion. A number of alpha-cyclopropyl thioketones were examined for their suitability as probes. These investigations were hampered by generally low thiophilic yields and the failure of the substrates examined to undergo ring openings independently characterizable as anionic or radical anionic as required for the successful diagnostic use of the cyclopropylcarbinyl-allylcarbinyl rearrangement. Cyclic voltammetry was examined as a technique to generate and characterize electrochemically the chemistry of the thioketyl radical anion of 1. These experiments indicated that 1 underwent an irreversible one electron reduction and permitted us to set the upper limit on the lifetime of this radical anion at <10('-2) sec at ambient temperatures. Evidence gathered from the reactions of 1 with organolithiums was presented which was consistent with a two electron thiophilic addition mechanism. Attempts to independently generate and unambiguously characterize the intermediates from 1 proposed to lie on the two electron and one electron reaction paths were unsuccessful.
The novel trilithiation of the alcohol 2 was reported and shown to proceed by sequential stereospecific gamma-oxyanion directed deprotonation of cyclopropyl groups to afford the unique trianionic species 3. Alkylation with methyl iodide gave the dimethylated product 4 in which the alkyl groups were suggested to be syn to the oxy function. Evidence was presented against monometalation followed by a rapid in situ metalation-alkylation sequence for the production of 4. Metalation and alkylation of 2 to afford compound 5 was also reported. The metallations were found to be suppressed by the addition of (N,N'-tetramethyl)ethylene diamine. This reaction
may provide methods for site selective metalation and alkylation of polyfunctional substrates.
(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI)
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1985.
|Date Available in IDEALS:||2014-12-15|