Synthesis of Spiro β-Lactams and Oxoindoles by Oxidative Dearomatization

Significance

Reported is the synthesis of spiro β-lactams and oxoindoles by oxidative dearomatization of phenolic acetanilides. Following the lead of similar strategies developed by Kita for oxidative C-N coupling (Chem. Commun. 2007, 1224), the present group developed conditions for the conversion of phenolic amide 3 into spiro β-lactams 4 combining the CuSO₄˙5H₂O, iodobenzene diacetate (IDB) and DMAP reagents. The reaction pathway may involve a radical coupling pathway involving oxidation reactions of IBD and CuSO₄˙5H₂O (H. Eickhoff, G. Jung, A. Rieker ­Tetrahedron 2001, 57, 353). However, an ionic pathway cannot be excluded. Using the phenolic amide 5 as starting material, similar conditions for obtaining oxoindoles 6 were developed which, however, were not isolated but converted into the corresponding oxoindoles 7 by treatment with TsOH.