Hydroxytyrosol, a polyphenol with very interesting antioxidant properties, which naturally occurs in virgin olive oil and mainly in olive oil mill waste waters, was synthesized by reducing 3, 4-dihydroxyphenylacetic acid with LiAlH(4) in tetrahydrofuran under refluxing for 2 h. The yield of reaction was 82.8%. The spectroscopic and HPLC data of the synthesized compound proved to coincide fully with those of a pure sample obtained by the chromatographic recovery from olive oil mill waste waters (yield = 91 mg/L). This synthetic method appears to be the most convenient compared with those reported in the literature and is more convenient than the chromatographic recovery. The tri- and diacetyl derivatives of the synthetic compound were also prepared for structure-bioactivity relationship studies. A brief discussion is given on the economical and ecological aspects regarding the production of hydroxytyrosol.
The iodine-magnesium exchange reaction allows the preparation of polyfunctional aryl, heteroaryl, or alkenyl magnesium reagents at low temperature. These reagents display the typical reactivity of Grignard compounds and undergo various copper-catalyzed reactions such as allylation or 1,4-addition. Using this halogen-metal exchange reaction, it was possible to generate polyfunctional magnesium reagents on the solid phase.
New functionalized magnesium carbenoids bearing an ester function have been prepared via an iodine-magnesium exchange reaction. These new carbenoids react with various electrophiles (60-88% yield). A substituted magnesium carbenoid has been prepared by sulfoxide-magnesium exchange.
New immonium trifluoroacetates 1 and 2 react readily with functionalized organozinc or magnesium reagents leading to the corresponding aminomethylated products of type 5 and 7. The resulting bis-allylamines were deallylated leading to primary amines.
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