UBC Theses and Dissertations
Organogermane chemistry : preparation of reagents useful in synthesis Lemieux, René M.
This thesis is divided into three parts. The first part describes the preparation of regioisomerically pure functionalized 2-trimethylgermylalk-l-enes of general structure 26, which are useful in synthesis. The vinylgermane iodide 18, for example, has been shown in our laboratories to be a good synthetic equivalent to the but-l-ene d2,d4- and a2,d4-synthons 11 and 22, respectively. The preparation of the 2-trimethylgermylalk-l-enes of general structure 26 was accomplished via i) H2PtCl6 ,6H20 catalyzed addition of Me3GeH (53) to the carboncarbon triple bond of 1-trimethylsilylalk-l-ynes 52, and ii) treatment of the resultant product mixtures with /?-TsOH»H20 in dichloromethane. The second part delineates the new and experimentally simple preparation of MesGeLi (149) in THF solution. The novel reagent Me3GeCu»Me2S (168) was obtained by treatment of 149 with CuBr»Me2S. Me3GeCu»Me2S (168), in the presence of chlorotrimethylsilane, serves as a good reagent for the conversion of functionalized acyl chlorides of general structure 35 (X = Cl) into the acyltrimethylgermanes 37. Functionalized >S'-(pyridin-2-yl) thioesters of general structure 35 (X = ,S-(pyridin-2-yl)) also serve as good substrates for the preparation of acyltrimethylgermanes 37 with reagent 168. The acyltrimethylgermanes 37 are efficiently transformed into the 2-trimethylgermylalk-l-enes 26 via olefination with methylenetriphenylphosphorane. The third part of this thesis outlines the preparation of the novel (trimethylgermyl)- copper(I) reagents 222-225. The conjugate addition of reagents 222-225, as well as Me3GeCu»Me2S (168), to selected unsaturated carbonyl systems was investigated. The substances 229 and 234-238 were synthesized from the corresponding enones via 1,4-addition of the (trimethylgermyl)copper(I) reagents. The (E)-3-uimethylgermylalk-2-enoate 242 was prepared stereoselectively via 1,4-addition of reagents 168 or 223 onto the corresponding alk- 2-ynoate, whereas the (Z) isomer 243 was obtained predominantly when reagent 225 was employed. [Chemical Compound Diagrams]
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