Cycloallene, 9. 1‐Phenyl‐1‐aza‐3,4‐cyclohexadien, das erste Isodihydropyridin: Erzeugung und Abfangreaktionen

Cycloallenes, 9. — 1‐Phenyl‐1‐aza‐3,4‐cyclohexadiene, the First Isodihydropyridine: Generation and Interception The generation of the title cycloallene 4 from 6,6‐dibromo‐3‐phenyl‐3‐azabicyclo[3.1.0]hexane ( 10 ) with methyllithium according to the Doering‐Moore‐Skattebøl method is reported. In the presence of styrene, 1,3‐butadiene, furan, 1,3‐cyclohexadiene, and 1,3‐cyclopentadiene, 4 is intercepted in [2 + 2] and [4 + 2] cycloadditions with formation of the hexahydrocyclobuta[ c ]pyridines 6 and 11 and the hexahydroisoquinolines 12–15 , respectively. The starting compound 10 is prepared via the cis ‐disubstituted 1,1‐dibromocyclopropanes 8 and 9 from the known dioxepine derivative 7 , the synthesis of which has been considerably improved. On treatment with n ‐butyllithium, the dichlorophenylazabicyclohexane 3 is converted into 4 as well. However, in the competition for 4 , styrene is not successful against n ‐butyllithium, which transforms 4 into the pentadienylamine 5 .