Tetravinylethylene Derivatives: Synthesis and Applications
Creators: name: Horvath, Kelsey Leigh
Publisher: name: The Australian National University
Year: 2019
Subjects: Tetravinylethylene
hydrocarbon
synthesis

description: One of the major goals of synthetic organic chemistry is the pursuit of efficient synthesis. Synthetic methodology has targeted a myriad of molecules with varying degrees of complexity, most of which would be impractical to construct one covalent bond at a time. Consequently, strategies which enable the formation of several bonds at each step and thus reduce the overall number of steps in a reaction sequence are highly desirable. An attractive means of reaching this goal is the targeting of fundamental molecules, particularly hydrocarbons, with multiple degrees of unsaturation that permit highly efficient cascade reaction sequences. As a result, fundamental hydrocarbon chemistry is an intriguing field of study for researchers pursuing more efficient means of chemical synthesis. However, fundamental hydrocarbons and other such novel compounds are more than just a means to an end. Such compounds – many of which have been wrongly identified as prohibitively difficult to handle – can provide remarkable insights into the reactivity of relatively unstudied systems that can be applied to larger, more complex molecules. Tetravinylethylenes are a family of compounds that have attracted recent research interest within the Sherburn laboratory. While the first practical synthesis of the parent compound and some uniformly symmetrically substituted derivatives has been reported, no method exists or has been proposed towards the synthesis of unsymmetrically substituted tetravinylethylenes. Within Chapter 2 of this thesis, we report the successful implementation of a synthetic strategy permitting sequential installation of varying functional groups about the central tetravinylethylene framework. Our method has furnished over thirty examples of the first unsymmetrically substituted tetravinylethylenes. In addition, we demonstrate the use of these compounds in the rapid generation of complexity via a thermal electrocyclisation and site-selective Diels- Alder domino sequence. We also report the first examples of higher polyenic derivatives. While the parent tetravinylethylene and its dehydrogenated analogue, tetraethynylethylene, have enjoyed previous study in the literature including exploration of their physical and chemical properties, there are no reports detailing the synthesis of the five possible examples of partially dehydrogenated analogues of tetravinylethylene.These five postulated substrates may bear a combination of one alkene and three alkynes, three alkenes and one alkyne, or two alkenes and two alkynes around the central ethylene core. This latter possibility may be further imagined to arise via three different geometrical isomers. In Chapter 3, we report the synthesis of these five compounds for the first time, and display a preliminary study of their stabilities in relation to tetravinylethylene and tetraethynylethylene. We also report the preparation of the equivalent phenyl-substituted analogues in order to compare their stability with that of the five parent compounds. Various substituted analogues of four of the five compounds prepared through chemistry presented in Chapter 3 have been previously reported in the literature; however, with the exception of one isolated example, the gem-dienediyne framework has no substituted analogues reported. In Chapter 4 of this thesis, we report several substituted elaborations of the gem-dienediyne structure accessed via methodology reported in Chapter 2, and investigate their reactivity.