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
✍ Scribed by R. Fuks; R. Merenyi; H. G. Viehe
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 2010
- Weight
- 212 KB
- Volume
- 85
- Category
- Article
- ISSN
- 0037-9646
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✦ Synopsis
Abstract
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.