Aminobenzoannulated Hetero- and Carbocycles from 2-Azahepta-2,4-dien-6-ynyllithium Compounds: Scope and Limitation of a Novel Benzoannulation Reaction

Abstract

Deprotonation of the N-benzylhetarylmethanimines 9, 12, 15, and 18 at -78 °C with subsequent warming to room temperature over 16 hours and treatment with electrophiles furnished polysubstituted aminobenzoannulated heterocycles 19-25 in good to excellent yields. In a similar fashion, the deprotonation of the N-allyl-2-(alk-1-ynyl)phenylmethanimines 26 and 27 led to 2-vinylnaphthalen-1-amines 28 and 29, respectively, in moderate yields. The reaction of N-[(trimethylsilyl)methyl]imine 31 afforded naphthalen-1-amine 33, unsubstituted at the ortho position after removal of the trimethylsilyl group. The deprotonation of imine 34, bearing a trimethylsilyl group on the C≡C bond, gave none of expected amines, but the substituted imine 35, whose structure was identified using 2D NMR spectroscopy.

Key words

alkyne - amine - annulation - electrocyclic reaction - rearrangement

References

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• 15a

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Software program: Schakal (E. Keller), Freiburg, 2005; see http://www.krist.uni-freiburg.de/ki/Mitarbeiter/Keller/schakal.html (accessed May 24, 2007).

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CCDC 639286 (21) and 639287 (20) contain the supplementary crystallographic data for this paper. These data can be obtained free of charge at www.ccdc.cam.ac.uk/conts/retrieving.html [or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK, fax: [phone], E-mail: [e-mail]].