Bicyclo[2.2.2]octa-5,7-die-2-one (“Barrelenone”)

✍ Scribed by Prof. Dr. Rudolf Gompper; Dipl.-Chem. Karl-Heinz Etzbach

• Publisher: John Wiley and Sons
• Year: 1978
• Tongue: English
• Weight: 233 KB
• Volume: 17
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/anie.197806031

✦ Synopsis

Polar substituents influence the reactive behavior of ambifunctional anions and cations by inducing an alteration in charge distribution (allopolarization principle"]). The aroma-.ticity of a ring system can also alter the polarity and reactivity of an ambifunctional system. The same would appear to apply for bicycloaromaticity : reaction of the anion of bicyclo[4.2.2]decatrienone with dimethyl sulfate ['] gives a remarkably high yield of enol ether (0-methylation).

In continuation of our investigations on the alkylation of the dibenzobarrelenone anion (predominantly C-methylation, cf.

[I]), we have therefore synthesized bicyclo[2.2.2]octa-5,7dien-2-one (6) in order to study the alkylation of its anion bicyclo[2.2.2]octa-2,5,7-trien-2-olate.

On heating dihydrophthalic anhydride (1) (prepared from dihydrophthalic acid and acetic anhydride) with the acrylonitriles ( 2 a ) and ( 2 b ) (for the use of (2) as ketone equivalent cf. [31), 7-acetoxy-7-cyanobicyclo[2.2.2]octa-5-ene-2,3-dicarboxylic anhydride ( 3 a ) (45 %, yellow, amorphous powder) and the 7-chloro analog (3 b ) (50 %, colorless powder, m.p. 159-161 "C (from chloroform) are obtained, respectively.