|| The importance of the presence of butenolide groupings in biologically active substances has been recognized increasingly. (1) In our search for new pesticides we have prepared 26 α-arylamino-γ-aryl-⊿(α,β)-butenolides (1-26) and 9 α-arylidene-γ-aryl-⊿(α,β)-butenolides (27-35) which seemed to us of interest as test materials for the screening. α-Arylamino-γ-aryl-⊿(α,β)-butenolides were prepared by the reaction of sodium or potassium arylidenepyruvate with arylamines in the medium of glacial acetic acid as is reported by Meyer and Vaughan(2) (Scheme I, see also Experimental Section). α-Arylidene-γ-aryl-⊿(β,γ)-butenolides were prepared by the condensation of aromatic aldehydes with β-aroylpropionic acids in the presence of anhydrous sodium acetate. The analogous procedure for this purpose has been reported by several authors(3) (Scheme II). The physical properties, yields, and analytical data of these compounds have been summarized in Table I (1-26) and Table II (27-35).