Date of Award
Chemistry and Biochemistry
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The reaction of $\gamma$-benzyloxy-$\alpha,\beta$-unsaturated ketones with diiron nonacarbonyl afforded the corresponding $\eta\sp2$-iron tetracarbonyl alkene complexes selectively, without perceptible formation of $\eta\sp4$-iron tricarbonyl complexes. In the presence of boron trifluoride-etherate, these complexes formed $\eta\sp3$-allyl tetracarbonyliron cation intermediates, which reacted with silyl enol ethers, silyl ketene acetals, allyltributyltin, and an electron rich arene to afford 59a-d, 59e, 59f, and 59g, respectively. The regiochemistry of the reactions was exclusively $\gamma$- with respect to the carbonyl, and the geometrical stability of the allyl tetracarbonyliron cation intermediates allowed retention of configuration of the double bond. The substrates, $\gamma$-benzyloxy-$\alpha,\beta$-unsaturated ketones (55a-c), were prepared from propargyl alcohols, in four steps. Attempts were made to apply these homologous Michael reactions to the synthesis of the ring system of naturally occurring pyrenotides by preparing diketoesters 59b$\sp\prime$ from $\gamma$-benzyloxy-$\alpha,\beta$-unsaturated ketone (55b) and an appropriate silyl enol ether. The route, employing a silyl enol ether containing an alkynoate function, namely 69, failed to give a coupling product. Silyl enol ether (67), containing a Z-substituted alkenoate function failed to react in the intended manner. Trimethylsilyl enol ether (61), bearing an E-substituted alkenoate function, did react to give the expected homo-Michael adduct (59b), albeit in low yield. Further investigation of this transformation, and its application in making natural products, is discussed.Dept. of Chemistry and Biochemistry. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1994 .Z475. Source: Masters Abstracts International, Volume: 34-02, page: 0767. Adviser: James R. Green. Thesis (M.Sc.)--University of Windsor (Canada), 1994.
Zhou, Tianhao., "Iron carbonyl-mediated Michael homologous reactions of gamma-alkoxy alkenones." (1994). Electronic Theses and Dissertations. 2519.