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Cationic polar cycloaddition with ynamines, formation of a ten‐membered nitrogen ring by twofold ynamine insertion into a 3,4‐dihydroisoquinolinium salt: A dihydrobenzo(d)azecine derivative and its rearrangement to a substituted tetrahydrobenzo(g)quinoline via 1,7‐sigmatropic hydrogen shift

par Fuks, Robert ;Merenyi, Robert;Viehe, Heinz Günter
Référence Bulletin des Sociétés chimiques belges, 85, 11, page (892-897)
Publication Publié, 1976

Article révisé par les pairs

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Résumé :

The reaction of 3,4‐dihydroisoquinolinium salt 11 with phenyl‐N,N‐dimethylaminoacetylene 12 affords the (1:2)‐adduct, the dihydrobenzo(d)azecinium salt derivative 13. The structure assignment is based on a preliminary X‐ray analysis as well as on analytical and spectral data. It is assumed that 11 forms with the ynamine a 1,4‐cationic polar system 14 which reacts with a second mole of ynamine 12 (now as polarophile) in a 42 cycloaddition to give compound 16. which rearranges to 13. Heating 13 in vacuo at 230‐265° leads to a dealkylation product having the tetrahydrobenzo(g)quinoline structure 19. Its formation can be explained by a 1,7‐hydrogen shift followed by an electrocyclisation of 17. Copyright © 1976 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim