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