A versatile and highly regioselective FeCl3-promoted tandem cyclization reaction of in situ generated alkynyl o-quinone methides (o-AQMs) with β-keto esters has been developed on the basis of the mode involving an intermolecular 1,4-conjugate addition/alkyne-allene isomerization/intramolecular transesterification/isomerization cascade. Using this method, a variety of diversely substituted 4-styryl-2H-chromen-2-ones were prepared with good efficiency and exclusive site-selectivity.
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http://dx.doi.org/10.1039/c9ob00323a | DOI Listing |
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