Degree Type

Dissertation

Date of Award

1982

Degree Name

Doctor of Philosophy

Department

Chemistry

Abstract

Organopolylithium compounds have recently been the subjects of numerous theoretical calculations which predicted intriguing structural features; among them is the planar geometry at C-1 of 1,1-dilithiocyclopropane, 21;Lithium (alpha)-lithiocyclopropanecarboxylate, a possible precursor to 21, was alkylated by iodomethane, allyl bromide, benzyl chloride or bromide in contrary to an earlier report. Treatments of 1,1-dibromotetramethylcyclopropane with excess n-butyllithium or t-butyllithium in various solvent systems showed no evidence for a consecutive double Li-Br exchange but the usual products from coupling, disproportionation, and exchange. Pentamethylcyclopropyl lithium and 2,2,3,3-tetramethylcyclopropyl lithium were iodinated unexpectedly with iodomethane;2,3-trans-Dimethoxymethyl-2,3-dimethylcyclopropylidene bromolithiocarbenoid, 72, were studied with ('13)C NMR (('13)C-enriched compound was used) and ('7)Li NMR. Spectroscopic evidences for the inversion at the carbenoid carbon and a mechanism for the inversion process were presented. Carbenoid 72 formed a hitherto unknown stable cyclopropylidene carbenoid: alkyllithium complex below -40(DEGREES)C with n-butyllithium. Treatments of 72 with t-butyllithium gave, among others, the 1,1-dilithio species whose C-1 was observed only by ('7)Li decoupled ('13)C NMR;1,1-Dibromotetramethylcyclopropane was converted to various 1-substituted-2,2,3,3-tetramethylcyclopropyl bromide, 99, by trapping the carbenoid with methanol, iodomethane, chlorotrimethylsilane, ethyl formate, acetic anhydride, chloro ethylformate, and carbon dioxide. Flash pyrolysis of 99 constituted a convenient method for the synthesis of functionalized 2,4-dimethyl-1,3-pentadienes;Electrophilic additions to 4.3.1propell-3-ene showed a preference for the endo approach. In case of 10,10-dibromo4.3.1propell-3-ene or allylic derivatives of 10,10-dibromo4.3.1propell-2-ene, the endo approach was exclusive regardless of the allylic substitution. The steric effect of the syn bromine was dominating and led to unexpected products.

DOI

https://doi.org/10.31274/rtd-180813-11857

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Diem Duy Le

Language

en

Proquest ID

AAI8307763

File Format

application/pdf

File Size

269 pages

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