Radicals derived from N-(alpha-xanthyl)acetanilides or N-(alpha-xanthyl)acetylaminopyridines possessing a substituent next to the nitrogen undergo a hitherto undocumented Smiles rearrangement proceeding through a four-membered ring. It was also found that under certain conditions the amidyl radical produced by cleavage of the four-membered ring intermediate can undergo fragmentation to give an isocyanate. Such fragmentations are unprecedented at temperatures corresponding to refluxing benzene or chlorobenzene.
An Efficient Synthesis of Aromatic Acetonyl Imines
作者:Joel Morris、Donn G. Wishka
DOI:10.1021/jo00113a057
日期:1995.4
INFLUENCE DE LA NATURE DES SUBSTITUANTS DANS LES REACTIONS D'EXTRUSION DE SOUFRE LORS DE L'ELABORATION DE LA CHARPENTE PYRIDO[2,3-<i>b</i>[1,4]THIAZEPINE
A strategy involving the reaction between an azaallylic anion linked to a chloropyridine and different O-ethyl thiocarboxylates has shown to be effective for the synthesis of 2-aryl and 2-heteroarylpyrido[2,3-b][1,4]thiazepine However the presence of a saturated cycle fused with the thiazepine ring results in distorsion of the parent molecule, thus weakening the conjugation, and consequently induces the sulfur extrusion from the preliminary formed cycloadduct giving rise finally to 1,5-naphthyridines.