Transition metal-free thiophene construction in pure water by multiplied C-H functionalization with enaminones and elemental sulfur

A novel method for the synthesis of 2,4-disubstituted thiophenes via the reactions of N,N -disubstituted enaminones and elemental sulfur is developed. By simply heating the substrates in pure water in the presence of NaOH, the thiophene annulation practically takes place via the generation of one C-C and two C-S bonds via cascade dual C-H functionalization and C-N bond thiolation without using any transition metal reagent. A brand-new cascade annulation reaction has been developed for the synthesis of 2,4-diacyl thiophenes via the reactions of enaminones and elemental sulfur. The products have been furnished with broad substrate scope via multiplied C-H bond functionalization without using any transition metal reagent in a pure water medium.