AbstractThe organolithium compounds, 1,4‐dilithio‐1,3‐diene and 1‐lithio‐1,3‐diene derivatives, show unprecedented reaction patterns with organic substrates. The 1,4‐dilithio‐1,3‐dienes react with aldehydes or ketones via deoxygenation of the C=O moieties to afford cyclopentadiene derivatives; pyridine derivatives are obtained in excellent yields when these organolithium reagents are treated with nitriles. In addition to novel reaction patterns, the experimental results have demonstrated that both the mono‐ and the dilithio reagents are synthetically useful building blocks. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)