Facile synthesis of multiply substituted cyclopentadienes and conjugated dienals through reactions between 1,4-dilithio-1,3-dienes and carboxylic acid derivatives including acyl chlorides, anhydrides, and DMF

摘要

Multiply substituted cyclopentadienes were formed through reactions between phenyl-substituted 1,4-dilithio-1,3-dienes such as 1b and 1c and two molecules of acyl chlorides. The phenyl substituents on the skeletons of the dilithiobutadiene derivatives played an essential role in the reaction pattern. Interestingly, when anhydrides were used, normal alkyl-substituted 1,4-dilithio-1,3-dienes such as la could also react similarly to the phenyl-substituted 1b and 1c, affording analogous types of multiply substituted cyclopentadienes in excellent isolated yields. Esters were found to afford mixtures of products when treated with la-c. When 1,4-dilithio-1,3-dienes wend treated with DMF, multiply substituted 2,4-diene-1,6-dials and/or 2,5-dihydrofuran derivatives were obtained in good yields, depending on the substitution patterns of the butadienyl skeletons. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007).