Intramolecular catalytic Friedel-Crafts reactions with allenyl cations for the synthesis of quinolines and their analogues.

[reaction: see text] This paper describes a novel method to synthesize a quinoline backbone by incorporating allenyl cations into a catalytic intramolecular Friedel-Crafts reaction. The initial products were isomerized and aromatized upon treatment with acid and base, respectively, to give quinolines. The basic concept also proved to be promising for 1-benzazepine, 1-benzazocine, or isoquinoline synthesis.

Dicobalt octacarbonyl promoted rearrangement of 4-isoxazolines to acylaziridines: dramatic rate acceleration with very high substrate tolerance.

[reaction: see text] Dicobalt octacarbonyl [Co(2)(CO)(8)] in acetonitrile at 75 degrees C triggers the cleavage of the N-O bond of 4-isoxazolines (1) to bring about the valence rearrangement to 2-acylaziridines (2). The isoxazolines were stable at 75 degrees C in the absence of the cobalt complex.