Reduction of Phenyl Silyl Acetylenes with Lithium: Unexpected Formation of a Dilithium Dibenzopentalenide

The degree of bulkiness of the silyl substituent strongly affects the reduction mode of phenyl silyl acetylenes. For example, the treatment of phenyl(triisopropylsilyl)acetylene with lithium led to the unprecedented formation of a dilithium dibenzopentalenide together with the expected 1,4-dilithio-1,3-butadiene (see scheme), whereas the reduction of phenyl(tert-butyldimethylsilyl)acetylene gave only the corresponding 1,4-dilithio-1,3-butadiene. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2007/z604067_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.