Using highly substituted isocyanides in the synthesis ofiminothiophenes fused to quinolines

In this manuscript the reaction of 2-mercaptoquinoline-3-carbaldehydes and 1,1,3,3-tetramethyl butylisocyanide as highly substituted isocyanide in the reflux of ethanol without catalyst is described. Formation of C-S, C-C and simultaneously oxidation towards thiophenone derivative is the advantage of this reaction. Also contrary to our impression using hindered isocyanides did not prevent the cyclisation. Only in one example when 2-mercapto quinoline-3-carbaldehyde was used in the reaction, the corresponding alpha keto amide was formed. All of the compounds are new so that they were characterized by mp, FT-IR, H and C-NMR and in some case the structure was confirmed by x-ray single crystallography.