A Pauson-Khand cycladdition of alkynes, alkenes, and carbon monoxide, promoted by cobalt carbonyl and nitrous oxide to furnish cyclopentenones is described. Preliminary mechanistic experiments suggest that nitrous oxide functions in a similar manner to the N-oxide promoters typically employed in Pauson-Khand reactions. Only dinitrogen and carbon dioxide are produced as a consequence of the activation mechanism, thus avoiding high molecular weight reagents and the build up of basic byproducts. The chemistry is done using equimolar amounts of alkyne, alkene, and dicobalt octacarbonyl, and is performed directly from the acetylenic component without having to presynthesize a cobalt-alkyne complex. Terminal acetylenes were suitable substrates, as was solid calcium carbide, and the corresponding adducts were isolated in good yields. Furthermore, two sequential [4+3] and [2+2+1] cycloadditions were performed, generating funtionalized cyclopentenones in only two steps from readily available starting materials.
Purpose: To evaluate the effect of growth hormones -naphthalene acetic acid (NAA) and indole-3-acetic acid (IAA) -on the essential oil of Sambucus ebulus leaf.
Methods: The leaves of S. ebulus were sprayed three times in one week with distilled water (as control) or with a solution of either NAA or IAA (150 ppb). Following the treatment, the leaves were collected from each of the plant and dried in the dark in a dry environment. The essential oil content of the leaves was obtained by hydrodistillation and analyzed by gas chromatography (GC) and GC-mass spectrometry (GC-MS)
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