Date of Award
Doctor of Philosophy
Philip M. Warner
The syntheses of 1,1-dilithioalkene, 1,2-dilithioalkene, and 1,2-dilithiocyclopropene derivatives have been attempted. The generation of a 1,1-dilithioalkene via double lithium-bromine exchange on 1,1-dibromo-3-methoxy-2-methoxymethylpropene with alkyllithiums was not successful. Quenching experiments did not provide enough evidence to prove the intermediacy of the 1,1-dilithio-3-methoxy-2-methoxymethylpropene. Two other routes, lithiation of the corresponding butatriene and 1,1-dimercurioalkene, were also studied but without success. A mechanism of reduction of carbenoid by BuLi was proposed.;The 1,2-dilithio-polyalkoxyalkenes were likely generated by the reaction of polyalkoxyalkynes with lithium. However, the presumed 1,2-dilithio-polyalkoxyalkenes not only did not dissolve in hydrocarbon or ether solvents, but also could not be isolated from the reaction mixture. The only evidence for the intermediacy of 1,2-dilithio-polyalkoxyalkenes was the quenching result.;When 1,1,2-tribromo-3,3-bismethoxymethylcyclopropene was treated with an excess amount of methyllithium, and quenched with various electrophiles, 1,2-disubsitutated cyclopropenes were found. The [superscript]13C NMR resonances of the lithiated carbon atoms in 1-lithio- and 1,2-dilithio-3,3-bismethoxymethylcyclopropene were recorded. Interestingly, 1-bromo-3,3-bismethoxymethylcyclopropene does not undergo lithium-bromine exchange with methyllithium; at higher temperature, a methylation reaction occurs instead.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Man, Hon-Wah, "Preparation and 13C NMR investigation of 1,1-dilithioalkenes, 1,2-dilithioalkenes, 1-lithiocyclopropenes and 1,2-dilithiocyclopropenes " (1990). Retrospective Theses and Dissertations. 9860.