Reactions of carbanions with 2,4‐dinitrofluorobenzene leading to stable heptatrienide moieties

Abstract

Abstract Reactions of NCCH 2 COOMe 1a and CH 2 (CN) 2 1b with 2,4‐dinitrofluorobenzene 2 at the presence of Et 3 N result in deeply colored crystalline stable salts 4a,4b with anions that contain a system of conjugated bonds. Similar reaction of 2 with phosphorus‐containing zwitterion 6 bearing ethoxy‐ and cyano‐groups at the carbanion center is the first example of the reaction leading to the formation of P‐zwitterion 9 with a negatively charged heptatriene moiety. This reaction proceeds via a new route of decomposition of the intermediate σ‐complex 7 occurring with formation of ethylfluoroformate. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:108–115, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20267