I. Thermal cyclization of (Z)-1,2,4-heptatrien-6-yne. II. Studies directed toward the synthesis of neocarzinostatin chromophore

• Main Author: Kuo, Elaine Y.
• Format: Others
• Language: en
• Published: 1993
• Online Access: https://thesis.library.caltech.edu/7387/2/Kuo_ey_1993.pdf; Kuo, Elaine Y. (1993) I. Thermal cyclization of (Z)-1,2,4-heptatrien-6-yne. II. Studies directed toward the synthesis of neocarzinostatin chromophore. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/x7qa-8x77. https://resolver.caltech.edu/CaltechTHESIS:01102013-092055513 <https://resolver.caltech.edu/CaltechTHESIS:01102013-092055513>

<p>The possibility that the hydrocarbon (Z)-1,2,4-heptatrien-6-yne might undergo a thermal cyclization to the biradical α,3-dehydroluene was considered. A methodology for the synthesis of (Z)-1,2,4-heptatrien-6-yne was developed wherein propargyl hydrazines, obtained from the corresponding propargyl alcohols, were oxidized to allenes with diethyl azodicarboxylate in good yields. The formation of products consistent with the intermediacy of the biradical α,3-dehydrotoluene is discussed.</p> <p>In studies directed toward the total synthesis of neocarzinostatin chromophore, the attempted formation of the cyclononadiyne core of the molecule via the intramolecular insertion of an alkylidene carbene into an acetylenic carbon-hydrogen bond was investigated. The alkylidene carbene was generated from the appropriately functionalized cyclopentanone precursor with the reagent dimethyl diazomethylphosphonate (DAMP). While the identification of the reaction products was consistent with the formation of the desired carbene, the formation of the desired insertion product was not observed. In conjunction with studies seeking to synthesize neocarzinostatin chromophore via an intramolecular acetylide addition, the synthesis of an epoxy carbonate fragment to be used in the convergent synthesis of a suitable cyclization precursor is described, as well as initial efforts concerning glycosylation with a suitably protected N-methyl D-fucosamine derivative.</p>