Browsing by Author "Haley, Michael Mark"

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    The synthesis and structure of cyclopropenes and cycloproparenes
    (1991) Haley, Michael Mark; Billups, W. Edward
    Tetra-n-butylammonium fluoride supported on glass helices was used to generate cyclopropenes in the gas phase from $\beta$-halocyclopropylsilanes using the vacuum gas-solid reaction (VGSR) technique. The following cyclopropenes were the target molecules, most of which were prepared successfully and in very good (55-85%) yields. The appropriate precursors were prepared by addition of a halo- or dihalocarbene to an alkenyltrimethylsilane. 1H,5H-Dicycloprop(b,h) anthracene (53) and 1H,4H-dicyclopropa(b,g) phenanthrene (54) were synthesized in 38% and 84% yield, respectively, by dehydrohalogenation with potassium t-butoxide in tetrahydrofuran at $-$20$\sp\circ$C. A key step in the syntheses was the Diels-Alder reaction of two equivalents of 1-bromo-2-chlorocyclopropene with the reactive 1,2,4,5- and 1,2,3,4-tetramethylenecyclohexanes.(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI) The corresponding dihydro derivatives 64 and 71 were prepared in 31% and 77% yield, respectively. The interesting cyclopropa(b) naphthalene derivative 69 was isolated in 57% yield. The starting compound for 69 was the major product from the reaction of 1-bromo-2-chlorocyclopropene with 1,2,3,4-tetramethylenecyclohexane.(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI) X-ray structural determinations were performed on cyclopropenes 48 and 49 and on cycloproparenes 24 and 40, in collaboration with Dr. Roland Boese at der Universitat Essen in Essen, Germany. The photoelectron spectrum of 49 was also obtained in collaboration with Prof. Rolf Gleiter at der Universitat Heidelberg in Heidelberg, Germany. These studies showed 49 to exhibit unusual bonding features.(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI)