Synthesis of the First Spirocyclopropabenzene

✍ Scribed by Prof. Dr. Heniz Dürr; Dipl.-Chem. Heribert Schmitz

• Publisher: John Wiley and Sons
• Year: 1975
• Tongue: English
• Weight: 104 KB
• Volume: 14
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/anie.197506471

✦ Synopsis

Dedicofrd t o Projissor Eugrn Miiller on the occasion of his 70fh birthday

Photofragmentation of diaza[4rr,4rc]-spirencs of type f 1 ) affords cyclopropa-benzenes or -naphthalenes of type (2) in good yielddtl.

By 1.3dipolar cycloaddition of diazocyclopentadiencs to cyclooctyne['' and subsequent photofragmentation we have succeeded analogously in synthesizing spirocyclopropabenzenes of type ( 4 ) . in which the cyclopropene ring should be still more strained--and the system thus more unstable-- than in cyclopropabenzenes of type ( 2 ) . Photolysis of the diaza-[4n.4n]-spirenes ( 3 0 ) --(3c)['I was carried out in ether at -20°C (with a high-pressure Hg lamp and a Pyrex filter): at the end of the quantitative evolution of nitrogen the spirocyclopropa benzenes ( 4 a )-( 4 c ) were obtained.