S. Woo et al., Indium-mediated gamma-pentadienylation of aldehydes and ketones: Cross-conjugated trienes for diene-transmissive cycloadditions, ORG LETT, 1(4), 1999, pp. 573-575
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Treatment of 5-bromo-1,3-pentadiene with indium metal in the presence of ca
rbonyl compounds results in gamma-pentadienylation to generate the 1,4-dien
e. Elimination of the resulting alcohol affords cross conjugated triene sys
tems which rapidly react with appropriate dienophiles to give tandem interm
olecular Diels-Alder adducts.