1,4‐Diphenyl‐1,3‐butadiene and 1,1,4,4‐Tetraphenyl‐1,3‐butadiene in the Reactions of Oxidative Sulfamidation and Trifluoroacetamidation

Sulfonamides react with 1,4‐diphenyl‐1,3‐butadiene in oxidative conditions to give the products of heterocyclization, substituted N‐sulfonylpyrrolidines. In contrast, 1,1,4,4‐tetraphenyl‐1,3‐butadiene with triflamide in the same conditions unexpectedly gives only 3,4,5,5‐tetraphenyldihydrofuran‐2(3 H )‐one as a result of oxidation/heterocyclization with migration of several phenyl groups. Oxidative trifluoroacetamidation of 1,4‐diphenyl‐1,3‐butadiene leads to a similar product of heterocyclization, N‐(trifluoroacetyl)pyrrolidine, but also to the product of oxyamidation at only one double bond and, unexpectedly, the product of splitting of the C=C bond, N,N′‐(phenylmethanediyl)bis(trifluoroacetamide), in a high total yield. Tentative mechanisms of the reactions are proposed.