Reactions of 3-substituted pentacyanines with cyclopentadienide and cyclononatetraenide anions

✍ Scribed by Wolfgang Bauer; Ulrich Müller-Westerhoff

• Book ID: 104236529
• Publisher: Elsevier Science
• Year: 1972
• Tongue: French
• Weight: 179 KB
• Volume: 13
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)84499-3

✦ Synopsis

Although it Is well known 1) that the condensation of 1-dialkylamino-penta-1.3-dienylidene-5dialkylammonium salts (pentacyanines &X=H) with sodium-cyclopentadienide leads to 6-(4-dialkylamino-1.3-butadienyl)fulvenes (&X=H), we expected that the use of substituted pentacyanines with suitable leaving groups at C-3 (&X=OTS,C~,N(CH~)~) would provide 2 as well as 6.6-bis-(2-dialkylaminovinyl)-fulvenes 2 , which interested us as potential intermediates for several non-benzenoid aromatics. Pyrone-4 (i)') served as starting material for the preparation of 9, 3-substituted pentacyaninea. Nucleophilic ringopening=' of 4 with dimethylamine afforded 1.5-bis-(dimethylamino)penta(1.4) dienone-(2). On treatment with p-toluenesulfonylchloride and sodium fluoroborate 2 was converted to a 3:l mixture of the 3-tosyloxy-and 3-chloro-pentacyanine fluoroborates 5 and 1. The formation of L, separated from 2 by fractional crystallization (CH2C12), can be understood as nucleophilic displacement of OTs-in 2 by chloride ions. \ Treatment of 6 with dimethylamine or alkylation of 2 with triethyloxonium fluoroborate, fol-lowed by reaction with dimethylamine, produced 1.3-bis-dimethylamino-penta-1.3-dianylidene-5dimethylammonium fluoroborate 8.