The Reaction of 2-Chloroazulene Derivatives with Lithium Acetylide in Liquid Ammonia

Abstract

Abstract The reaction of diethyl 2-chloroazulene-1,3-dicarboxylate (1a) with lithium acetylide in liq ammonia gave diethyl 4- and 6-ethynylazulene-1,3-dicarboxylates by an abnormal substitution reaction. In a similar manner, some 2-chloroazulenes, possessing alkoxycarbonyl and/or cyano substituents at the 1- and 3-positions of azulene nucleus, gave the corresponding 4 (or 8)- and 6-ethynylazulenes. The same type reaction proceeded when lithium phenylacetylide, sodium indenide, and sodium fluorenide were used as the reagents, 1a giving diethyl 4- and 6-(phenylethynyl)-, 6-(3-indenyl)-, and 6-(9-fluorenyl)azulene-1,3-dicarboxylates, respectively.