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

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.