An easy and convenient preparation of 2-amino-2-benzyl-3(2H)-benzofuranone and related compounds is described. The method utilizes the anomalous intramolecular conjugate addition of intermediate 2-amino-1-(2-hydroxyphenyl)-3-phenyl-2-propen-1-ones. 2-Benzyl-2-triphenylphosphoranylideneamino-3(2H)-benzofuranones by an analogous method are extremely unreactive and have limited synthetic applicability.
Racemic chiral O,N-heterocycles containing 2-arylchroman or 2-aryl-2H-chromene subunit condensed with morpholine, thiazole, or pyrrole moieties at the C-3-C-4 bond were synthesized with various substitution patterns of the aryl group by the cyclization of cis- or trans-3-aminoflavanone analogues. The 3-aminoflavanone precursors were obtained in a Neber rearrangement of oxime tosylates of flavanones