3,8-Methanoaza[10]annulene (Homoisoquinoline)

✍ Scribed by Dr. Werner Tückmantel; Gertraud Andree; Andreas Seidel; Dr. Hans Schmickler; Dr. Johann Lex; Dr. Elfi Kraka; Michael Haug; Prof. Dr. Dieter Cremer; Prof. Dr. Emanuel Vogel

• Publisher: John Wiley and Sons
• Year: 1985
• Tongue: English
• Weight: 399 KB
• Volume: 24
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/anie.198505921

✦ Synopsis

differs from the latter in that it has a flat chair conformation. The median planes of the two [IOJannulene rings !n 3b are at a slightly different level (difference ca. 0.6 A) which can be explained in terms of the geometry of 6, [14] In the meantime, it has been shown that the syn-isomer 3a (sydanti-isomeric ratio 1 :4) is also formed in the oxidative coupling of 5. 3a initially escaped detection, because it polymerized on the carrier material during chromatography. The isolation of 3a has now been made possible by the surprising finding that the dibromide 4, on reaction with NiCI2(PPh&, zinc, and tetraethylammonium iodide in tetrahydrof~ran['~] (I h at S O T ) forms syn-and anti-bishomoperylene in the ratio of 4:3. After chromatographic separation on silica gel (hexane), 3a is recrystallized from ethanol to give fine, red crystals [decamp. above 200°C; yield 7%]. 3b is obtained in 18% yield via this route.

3a was identified mainly by its 'H-NMR spectrum, since this is almost identical to the spectrum of 3b, except for the resonance signals of H-4, H-4' and H-8, H-8', which, as expected, are shifted further downfield (by 0.3 ppm) (see Table I).