Synthesis and acid-base transformations of 8-substituted 10-phenyl-10-hydroxy-10H- pyrido [2,3-b ]chromenes

The corresponding 2-(p-substituted phenoxy)-3-aroylpyridines were obtained by the reaction of 2-(p-substituted phenoxy)nicotinonitriles with phenylmagnesium bromide. It is shown that they are readily cyclized to 8-substituted 10-phenyl-10-hydroxy-10H-pyrido2,3-b]chromenes by the action of concentrated sulfuric acid in glacial acetic acid. The pK_R+ values of the cyclization products, which range from–7.70 to –10.83 and correlate with the _p ⁰ substituent constants, were determined by spectrophotometry.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 614–616, May, 1982.