Isoimidium salts derived from diphenylmethylenesuccinic acid and their conjugate bases. Ene-type reactions involving transfer of acyl groups

Abstract

The amic acids (2a–d), obtained from diphenylmethylenesuccinic anhydride and amines, were converted into the isoimidium perchlorates (4a–d). Deprotonation of the ternary salts yielded the isolable butenolides (5a–c), which formed ene-type adducts (8) and (9) with aromatic aldehydes and carbon disulphide, respectively. The action of arenediazonium salts led to novel 1-aryl-4-diphenylmethylene-4H-pyrazolin-5-ones (11). A different type of diphenylmethylenesuccinisoimidium salt, compound (12), was prepared and attempts to convert it into the cross-conjugated 1,3-dipole (13) are described. The action of acetic anhydride on the 1-monomorpholide (3a) of diphenylmethylenesuccinic acid results in the formation of 1-acetoxy-3-morpholinocarbonyl-4-phenylnaphthalene (20a)via a mixed anhydride.