• Lithiation occurs at the 2-position. For the formation of furfuryl propargyl ethers and their subsequent base catalyzed intramolecular Diels-Alder cyclization to isobenzofuran derivatives, see: J. Org. Chem., 60,6168 (1995). 2,5-Dilithiation can be effected with n-BuLi - TMEDA: J. Chem. Soc., Perkin 1, 887 (1977), or n-BuLi - KO-t-Bu: Synthesis, 316 (1988). A Barbier-type reaction has been reported in which furan is reacted with a lithium carboxylate in the presence of Li metal and t-butyl chloride with sonication: J. Org. Chem., 60, 8 (1995), providing an easy access to 2-furyl ketones.
• Diels-Alder cycloadditions of furans with reactive dienophiles, followed by dehydration of the resulting 7-oxabicyclo[2.2.1]heptenes generate benzenes, often with unusual substitution patterns; review: Heterocycles, 22, 875 (1984). Adducts of furans with alkynes can be deoxygenated to give aromatics, by reduction with a low-valent Ti reagent: Synthesis, 787 (1984).