An efficient protocol toward trisubstituted 3‐aminothiophenes has been developed through a [4+1] cycloaddition of enaminothiones and aldehydeN‐tosylhydrazones under transition‐metal‐free conditions. 3‐Aminothiophene derivatives as well as their chiral analogs were obtained in good to excellent yields. Direct interaction of the enaminothiones with the diazo compounds of α‐carbonyl or ester group‐functionalized
Copper-Catalyzed Formal Carbene Migratory Insertion into Internal Olefinic C═C Bonds with <i>N</i>-Tosylhydrazones To Access Iminofuran and 2(3<i>H</i>)-Furanone Derivatives
α-oxo ketene N,S-acetals, has been achieved by means of N-tosylhydrazones of ketones as the carbene precursors. Iminofuran derivatives were obtained and further transformed to the corresponding 2(3H)-furanones and 4-oxobutanoates (γ-ketoesters), respectively, under mild conditions. In a similar fashion, α-thioxo ketene N,S-acetals reacted with N-tosylhydrazones of ketones to afford iminothiophenes. It
A novel method for the synthesis of N-alkyl-3-acyl-4-alkoxycarbonylmethylpyrrolidine-2,5-diones (3) was accomplished. α-Oxoketene O,N-acetals (1) reacted with maleicanhydride (2) at 80–110 °C for 5 h without solvent to give 3 in moderate to good yield (36–74%). Single X-ray crystallographic analysis showed that the two substituents on C-3 and C-4 were trans.
alpha-Oxoketene O,N-acetals were prepared from beta-oxothiono esters and primary amines in the presence of triethylamine at room temperature within several hours in good yields.